Fix more errors with msys2 ucrt platform

_mkdir being undefined:

    [ 81%] Building C object src/CMakeFiles/madx.dir/mad_sstate.c.obj
    C:\Users\Thomas\dev\hit\cpymad\src\MAD-X\src\mad_sstate.c: In function 'store_state':
    C:\Users\Thomas\dev\hit\cpymad\src\MAD-X\src\mad_sstate.c:42:5: error: implicit declaration of function '_mkdir'; did you mean 'mkdir'? [-Wimplicit-function-declaration]
       42 |     _mkdir(dir_name);
          |     ^~~~~~
          |     mkdir

and lots of undefined symbols (ad_alloc_, ad_free_, ...) in PTC.

.github/patch/fix-madx-win32.patch

@@ -0,0 +1,23 @@
+diff --git a/libs/ptc/src/tpsa.h b/libs/ptc/src/tpsa.h
+index 4a2f15bc..b0b3174c 100644
+--- a/libs/ptc/src/tpsa.h
++++ b/libs/ptc/src/tpsa.h
+@@ -11,7 +11,7 @@
+ //! \version $Id: tpsa.h,v 1.4 2009-04-17 17:32:23 frs Exp $
+ //! \author Lingyun Yang, http://www.lingyunyang.com/
+
+-#ifndef WIN32
++#if !defined(WIN32) || defined(__GNUC__)
+
+ /* should work unchanged on _win32 using Lahey */
+ #define ad_print      ad_print_
+diff --git a/src/mad_sstate.c b/src/mad_sstate.c
+index fe909635..044ed409 100644
+--- a/src/mad_sstate.c
++++ b/src/mad_sstate.c
+@@ -1,4 +1,5 @@
+ #include "madx.h"
++#include <direct.h>     // _mkdir()
+
+ static void
+ move_files(const char* orig_name,const  char* append,const  char* dirname){

.github/workflows/build.yml

@@ -119,6 +119,9 @@ jobs:
           src/MAD-X -b $MADX_VERSION --depth 1
         if: steps.madx-build-cache.outputs.cache-hit != 'true'
 
+      - name: Apply patches
+        if: steps.madx-build-cache.outputs.cache-hit != 'true'
+        run: patch -d src/MAD-X -p1 <.github/patch/fix_mkdir.patch
       - name: Build MAD-X
         if: steps.madx-build-cache.outputs.cache-hit != 'true'
         run: .github/build/windows/madx.sh src/MAD-X