FindPython: enhance ABI checks against include directory

Fixes: #21149

Modules/FindPython/Support.cmake

@@ -607,14 +607,24 @@ function (_PYTHON_GET_VERSION)
           # ABI not used on Windows
           set (abi "")
         else()
-          if (config MATCHES "#[ ]*define[ ]+Py_DEBUG[ ]+1")
-            string (APPEND abi "d")
-          endif()
-          if (config MATCHES "#[ ]*define[ ]+WITH_PYMALLOC[ ]+1")
-            string (APPEND abi "m")
-          endif()
-          if (config MATCHES "#[ ]*define[ ]+Py_UNICODE_SIZE[ ]+4")
-            string (APPEND abi "u")
+          if (NOT config)
+            # pyconfig.h can be a wrapper to a platform specific pyconfig.h
+            # In this case, try to identify ABI from include directory
+            if (_${_PYTHON_PREFIX}_INCLUDE_DIR MATCHES "python${version_major}\.${version_minor}+([dmu]*)")
+              set (abi "${CMAKE_MATCH_1}")
+            else()
+              set (abi "")
+            endif()
+          else()
+            if (config MATCHES "#[ ]*define[ ]+Py_DEBUG[ ]+1")
+              string (APPEND abi "d")
+            endif()
+            if (config MATCHES "#[ ]*define[ ]+WITH_PYMALLOC[ ]+1")
+              string (APPEND abi "m")
+            endif()
+            if (config MATCHES "#[ ]*define[ ]+Py_UNICODE_SIZE[ ]+4")
+              string (APPEND abi "u")
+            endif()
           endif()
           set (${_PGV_PREFIX}ABI "${abi}" PARENT_SCOPE)
         endif()