gh-144490: Fix mimalloc debug build for C++ (#144620)

Author: yoney

Include/internal/mimalloc/mimalloc/types.h

@@ -608,8 +608,8 @@ struct mi_heap_s {
 
 #if (MI_DEBUG)
 // use our own assertion to print without memory allocation
-mi_decl_noreturn mi_decl_cold mi_decl_throw
-void _mi_assert_fail(const char* assertion, const char* fname, unsigned int line, const char* func);
+mi_decl_noreturn mi_decl_cold
+void _mi_assert_fail(const char* assertion, const char* fname, unsigned int line, const char* func) mi_decl_throw;
 #define mi_assert(expr)     ((expr) ? (void)0 : _mi_assert_fail(#expr,__FILE__,__LINE__,__func__))
 #else
 #define mi_assert(x)

Lib/test/test_cppext/extension.cpp

@@ -15,10 +15,8 @@
 #ifdef TEST_INTERNAL_C_API
    // gh-135906: Check for compiler warnings in the internal C API
 #  include "internal/pycore_frame.h"
-   // mimalloc emits many compiler warnings when Python is built in debug
-   // mode (when MI_DEBUG is not zero).
    // mimalloc emits compiler warnings when Python is built on Windows.
-#  if !defined(Py_DEBUG) && !defined(MS_WINDOWS)
+#  if !defined(MS_WINDOWS)
 #    include "internal/pycore_backoff.h"
 #    include "internal/pycore_cell.h"
 #  endif