Avoid JIT warning with opcache.jit_buffer_size=0

Closes GH-12460

Author: iluuu1994

ext/opcache/ZendAccelerator.c

@@ -3270,7 +3270,11 @@ static zend_result accel_post_startup(void)
 			 || zend_jit_startup(ZSMMG(reserved), jit_size, reattached) != SUCCESS) {
 				JIT_G(enabled) = 0;
 				JIT_G(on) = 0;
-				zend_accel_error(ACCEL_LOG_WARNING, "Could not enable JIT!");
+				/* The JIT is implicitly disabled with opcache.jit_buffer_size=0, so we don't want to
+				 * emit a warning here. */
+				if (JIT_G(buffer_size) != 0) {
+					zend_accel_error(ACCEL_LOG_WARNING, "Could not enable JIT!");
+				}
 			}
 		}
 #endif

ext/opcache/tests/jit_warning_with_zero_buffer.phpt

@@ -0,0 +1,16 @@
+--TEST--
+JIT should not emit warning with opcache.jit_buffer_size=0
+--INI--
+opcache.enable=1
+opcache.enable_cli=1
+opcache.jit=tracing
+opcache.jit_buffer_size=0
+opcache.log_verbosity_level=2
+--EXTENSIONS--
+opcache
+--FILE--
+<?php
+var_dump(opcache_get_status()['jit']['enabled'] ?? false);
+?>
+--EXPECT--
+bool(false)