Fix: Python warning in windows debug builds

When doing a debug build on windows, blender will
start with the following warning:

"Unable to find the python binary, the multiprocessing
module may not be functional!"

The root cause for this issue is: for a debug build
the python binary is called python_d.exe rather than
just python.exe

This change fixes BKE_appdir_program_python_search
to look for the _d suffix for debug builds on windows

Differential Revision: https://developer.blender.org/D9775

Reviewed by: Campbell Barton

source/blender/blenkernel/intern/appdir.c

@@ -906,14 +906,20 @@ bool BKE_appdir_program_python_search(char *fullpath,
   const char *python_build_def = STRINGIFY(PYTHON_EXECUTABLE_NAME);
 #endif
   const char *basename = "python";
+#if defined(WIN32) && !defined(NDEBUG)
+  const char *basename_debug = "python_d";
+#endif
   char python_version[16];
   /* Check both possible names. */
   const char *python_names[] = {
 #ifdef PYTHON_EXECUTABLE_NAME
-      python_build_def,
+    python_build_def,
 #endif
-      python_version,
-      basename,
+#if defined(WIN32) && !defined(NDEBUG)
+    basename_debug,
+#endif
+    python_version,
+    basename,
   };
   bool is_found = false;