Add PC/ to CPPFLAGS and to SRCDIRS on Mingw

Co-authored-by: Naveen M K <naveen521kk@gmail.com>

configure.ac

@@ -6470,6 +6470,16 @@ do
   THREADHEADERS="$THREADHEADERS \$(srcdir)/$h"
 done
 
+case $host in
+  *-*-mingw*)
+    dnl Required for windows builds as Objects/exceptions.c require
+    dnl "errmap.h" from $srcdir/PC.
+    dnl Note we cannot use BASECPPFLAGS as autogenerated pyconfig.h
+    dnl has to be before customized located in ../PC.
+    CPPFLAGS="-I\$(srcdir)/PC $CPPFLAGS"
+    ;;
+esac
+
 AC_SUBST(SRCDIRS)
 SRCDIRS="\
   Modules \
@@ -6491,6 +6501,10 @@ SRCDIRS="\
   Python \
   Python/frozen_modules \
   Python/deepfreeze"
+case $host in
+  *-*-mingw*) SRCDIRS="$SRCDIRS PC";;
+esac
+
 AC_MSG_CHECKING(for build directories)
 for dir in $SRCDIRS; do
     if test ! -d $dir; then