Removed use of CODE_COVERAGE environment variable

CODE_COVERAGE was used to influence whether the backend SyclInterface library
was built in debug mode with coverage over dpctp-capi/ test suite collected or not.

It was also influencing how Cython extensions were built. It would pass linetrace=true
option to cythonize, and define CYTHON_TRACE preprocessor variable when compiling
Cython-generated C++ source files with compiler.

This change removes use CODE_COVERAGE all together. Instead:

1. Custom setuptools command 'build_ext' is implemented which auto-adds
   'CYTHON_TRACE' to the list of defines received by downstream build_ext
   command if develop command received --coverage=True

   cythonize call was removed from extensions() function, allowing
   ``python setup.py develop --help` execute cleanly without running
   cythonize.

   Consequentially, linetrace Cython directive will need to be added to
   each .pyx file in a separate commit.  This is safe to do per

   https://cython.readthedocs.io/en/latest/src/tutorial/profiling_tutorial.html#enabling-line-tracing

   since it is a no-op unless CYTHON_TRACE preprocessor variable is also set,
   which is only done when --coverage=True is used

2. install setuptools command removed support for `--coverage` option, and always
   builds backend without coverage.

   This is to avoid inadvertent installation of debug build of library in Python prefix.

Author: oleksandr-pavlyk

setup.py

@@ -19,9 +19,9 @@
 import sys
 
 import numpy as np
+import setuptools.command.build_ext as orig_build_ext
 import setuptools.command.develop as orig_develop
 import setuptools.command.install as orig_install
-from Cython.Build import cythonize
 from setuptools import Extension, find_packages, setup
 
 import versioneer
@@ -39,6 +39,9 @@
 else:
     assert False, "We currently do not build for " + sys.platform
 
+# global variable used to pass value of --coverage option of develop command
+# to build_ext command
+_coverage = False
 dpctl_sycl_interface_lib = "dpctl"
 dpctl_sycl_interface_include = r"dpctl/include"
 
@@ -123,7 +126,6 @@ def extensions():
     ela = get_sdl_ldflags()
     libs = []
     libraries = []
-    CODE_COVERAGE = os.environ.get("CODE_COVERAGE")
 
     if IS_LIN:
         libs += ["rt", "DPCTLSyclInterface"]
@@ -160,15 +162,6 @@ def extensions():
         "define_macros": [],
     }
 
-    if CODE_COVERAGE:
-        extension_args.update(
-            {
-                "define_macros": [
-                    ("CYTHON_TRACE", "1"),
-                ]
-            }
-        )
-
     extensions = [
         Extension(
             "dpctl._sycl_context",
@@ -253,15 +246,25 @@ def extensions():
             define_macros=extension_args["define_macros"],
         ),
     ]
-    if CODE_COVERAGE:
-        exts = cythonize(
-            extensions,
-            compiler_directives={"linetrace": True},
-            language_level=3,
-        )
-    else:
-        exts = cythonize(extensions, language_level=3)
-    return exts
+    # ext = cythonize(extensions, language_level=3)
+    return extensions
+
+
+class build_ext(orig_build_ext.build_ext):
+    description = "Build dpctl native extensions"
+
+    def finalize_options(self):
+        global _coverage
+        if _coverage:
+            pre_d = getattr(self, "define", None)
+            if pre_d is None:
+                self.define = "CYTHON_TRACE"
+            else:
+                self.define = ",".join((pre_d, "CYTHON_TRACE"))
+        super().finalize_options()
+
+    def run(self):
+        return super().run()
 
 
 class install(orig_install.install):
@@ -279,18 +282,11 @@ class install(orig_install.install):
             "Path to SYCL compiler installation. None means "
             "read it off ONEAPI_ROOT environment variable or fail.",
         ),
-        (
-            "coverage=",
-            None,
-            "Whether to generate coverage report "
-            "when building the backend library",
-        ),
     ]
 
     def initialize_options(self):
         super().initialize_options()
         self.level_zero_support = "True"
-        self.coverage = os.getenv("CODE_COVERAGE", "False")
         self.sycl_compiler_prefix = None
 
     def finalize_options(self):
@@ -302,12 +298,6 @@ def finalize_options(self):
             raise ValueError(
                 "--level-zero-support value is invalid, use True/False"
             )
-        if isinstance(self.coverage, str):
-            self.coverage = self.coverage.capitalize()
-        if self.coverage in ["True", "False", "0", "1"]:
-            self.coverage = bool(eval(self.coverage))
-        else:
-            raise ValueError("--coverage value is invalid, use True/False")
         if isinstance(self.sycl_compiler_prefix, str):
             if not os.path.exists(os.path.join(self.sycl_compiler_prefix)):
                 raise ValueError(
@@ -326,9 +316,7 @@ def finalize_options(self):
         super().finalize_options()
 
     def run(self):
-        build_backend(
-            self.level_zero_support, self.coverage, self.sycl_compiler_prefix
-        )
+        build_backend(self.level_zero_support, False, self.sycl_compiler_prefix)
         return super().run()
 
 
@@ -358,7 +346,7 @@ class develop(orig_develop.develop):
     def initialize_options(self):
         super().initialize_options()
         self.level_zero_support = "True"
-        self.coverage = os.getenv("CODE_COVERAGE", "False")
+        self.coverage = "False"
         self.sycl_compiler_prefix = None
 
     def finalize_options(self):
@@ -374,6 +362,8 @@ def finalize_options(self):
             self.coverage = self.coverage.capitalize()
         if self.coverage in ["True", "False", "0", "1"]:
             self.coverage = bool(eval(self.coverage))
+            global _coverage
+            _coverage = self.coverage
         else:
             raise ValueError("--coverage value is invalid, use True/False")
         if isinstance(self.sycl_compiler_prefix, str):
@@ -404,6 +394,7 @@ def _get_cmdclass():
     cmdclass = versioneer.get_cmdclass()
     cmdclass["install"] = install
     cmdclass["develop"] = develop
+    cmdclass["build_ext"] = build_ext
     return cmdclass