msvcrt: Convert the open functions to use MS ABI varargs.

dlls/msvcrt/file.c

@@ -1418,7 +1418,7 @@ int CDECL MSVCRT__pipe(int *pfds, unsigned int psize, int textmode)
  */
 int CDECL MSVCRT__sopen( const char *path, int oflags, int shflags, ... )
 {
-  va_list ap;
+  __ms_va_list ap;
   int pmode;
   DWORD access = 0, creation = 0, attrib;
   DWORD sharing;
@@ -1440,9 +1440,9 @@ int CDECL MSVCRT__sopen( const char *path, int oflags, int shflags, ... )
 
   if (oflags & MSVCRT__O_CREAT)
   {
-    va_start(ap, shflags);
-      pmode = va_arg(ap, int);
-    va_end(ap);
+    __ms_va_start(ap, shflags);
+    pmode = va_arg(ap, int);
+    __ms_va_end(ap);
 
     if(pmode & ~(MSVCRT__S_IREAD | MSVCRT__S_IWRITE))
       FIXME(": pmode 0x%04x ignored\n", pmode);
@@ -1516,12 +1516,12 @@ int CDECL MSVCRT__wsopen( const MSVCRT_wchar_t* path, int oflags, int shflags, .
 {
   const unsigned int len = strlenW(path);
   char *patha = MSVCRT_calloc(len + 1,1);
-  va_list ap;
+  __ms_va_list ap;
   int pmode;
 
-  va_start(ap, shflags);
+  __ms_va_start(ap, shflags);
   pmode = va_arg(ap, int);
-  va_end(ap);
+  __ms_va_end(ap);
 
   if (patha && WideCharToMultiByte(CP_ACP,0,path,len,patha,len,NULL,NULL))
   {
@@ -1539,14 +1539,14 @@ int CDECL MSVCRT__wsopen( const MSVCRT_wchar_t* path, int oflags, int shflags, .
  */
 int CDECL MSVCRT__open( const char *path, int flags, ... )
 {
-  va_list ap;
+  __ms_va_list ap;
 
   if (flags & MSVCRT__O_CREAT)
   {
     int pmode;
-    va_start(ap, flags);
+    __ms_va_start(ap, flags);
     pmode = va_arg(ap, int);
-    va_end(ap);
+    __ms_va_end(ap);
     return MSVCRT__sopen( path, flags, MSVCRT__SH_DENYNO, pmode );
   }
   else
@@ -1560,12 +1560,12 @@ int CDECL _wopen(const MSVCRT_wchar_t *path,int flags,...)
 {
   const unsigned int len = strlenW(path);
   char *patha = MSVCRT_calloc(len + 1,1);
-  va_list ap;
+  __ms_va_list ap;
   int pmode;
 
-  va_start(ap, flags);
+  __ms_va_start(ap, flags);
   pmode = va_arg(ap, int);
-  va_end(ap);
+  __ms_va_end(ap);
 
   if (patha && WideCharToMultiByte(CP_ACP,0,path,len,patha,len,NULL,NULL))
   {