Patch for warnings in 64bit Windows builds

[Andy Moreton <andrewjmoreton@gmail.com>]

Hi,

The 64bit Windows builds have shown a few warnings for some time:

../../src/w32proc.c: In function 'w32_compare_strings':
../../src/w32proc.c:3526:20: warning: assignment from incompatible pointer type [-Wincompatible-pointer-types]
    pCompareStringW = GetProcAddress (LoadLibrary ("Unicows.dll"),
                    ^
../../src/w32fns.c: In function 'Ffile_system_info':
../../src/w32fns.c:7827:9: warning: initialization from incompatible pointer type [-Wincompatible-pointer-types]
       = GetProcAddress (hKernel, "GetDiskFreeSpaceExW");
         ^
../../src/w32fns.c:7830:9: warning: initialization from incompatible pointer type [-Wincompatible-pointer-types]
       = GetProcAddress (hKernel, "GetDiskFreeSpaceExA");
         ^
The following patch builds cleanly on:
  - 32bit mingw
  - 32bit mingw --with-wide-int
  - 64bit mingw64

I don't have copyright paperwork on file, so please let me know if that
is required.

    AndyM

diff --git a/src/w32fns.c b/src/w32fns.c
index abfa315e2a96..499450f4c927 100644
--- a/src/w32fns.c
+++ b/src/w32fns.c
@@ -7799,6 +7799,11 @@ The following %-sequences are provided:
 
 \f
 #ifdef WINDOWSNT
+typedef BOOL (WINAPI *GetDiskFreeSpaceExW_Proc)
+  (LPCWSTR, PULARGE_INTEGER, PULARGE_INTEGER, PULARGE_INTEGER);
+typedef BOOL (WINAPI *GetDiskFreeSpaceExA_Proc)
+  (LPCSTR, PULARGE_INTEGER, PULARGE_INTEGER, PULARGE_INTEGER);
+
 DEFUN ("file-system-info", Ffile_system_info, Sfile_system_info, 1, 1, 0,
        doc: /* Return storage information about the file system FILENAME is on.
 Value is a list of floats (TOTAL FREE AVAIL), where TOTAL is the total
@@ -7822,12 +7827,10 @@ If the underlying system call fails, value is nil.  */)
      added rather late on.  */
   {
     HMODULE hKernel = GetModuleHandle ("kernel32");
-    BOOL (WINAPI *pfn_GetDiskFreeSpaceExW)
-      (wchar_t *, PULARGE_INTEGER, PULARGE_INTEGER, PULARGE_INTEGER)
-      = GetProcAddress (hKernel, "GetDiskFreeSpaceExW");
-    BOOL (WINAPI *pfn_GetDiskFreeSpaceExA)
-      (char *, PULARGE_INTEGER, PULARGE_INTEGER, PULARGE_INTEGER)
-      = GetProcAddress (hKernel, "GetDiskFreeSpaceExA");
+    GetDiskFreeSpaceExW_Proc pfn_GetDiskFreeSpaceExW =
+      (GetDiskFreeSpaceExW_Proc) GetProcAddress (hKernel, "GetDiskFreeSpaceExW");
+    GetDiskFreeSpaceExA_Proc pfn_GetDiskFreeSpaceExA =
+      (GetDiskFreeSpaceExA_Proc) GetProcAddress (hKernel, "GetDiskFreeSpaceExA");
     bool have_pfn_GetDiskFreeSpaceEx =
       ((w32_unicode_filenames && pfn_GetDiskFreeSpaceExW)
        || (!w32_unicode_filenames && pfn_GetDiskFreeSpaceExA));
diff --git a/src/w32proc.c b/src/w32proc.c
index ca4322b69d16..66a9761ad138 100644
--- a/src/w32proc.c
+++ b/src/w32proc.c
@@ -3327,16 +3327,16 @@ yield nil.  */)
   (Lisp_Object cp)
 {
   CHARSETINFO info;
-  DWORD dwcp;
+  DWORD_PTR dwcp;
 
   CHECK_NUMBER (cp);
 
   if (!IsValidCodePage (XINT (cp)))
     return Qnil;
 
-  /* Going through a temporary DWORD variable avoids compiler warning
+  /* Going through a temporary DWORD_PTR variable avoids compiler warning
      about cast to pointer from integer of different size, when
-     building --with-wide-int.  */
+     building --with-wide-int or building for 64bit.  */
   dwcp = XINT (cp);
   if (TranslateCharsetInfo ((DWORD *) dwcp, &info, TCI_SRCCODEPAGE))
     return make_number (info.ciCharset);
@@ -3499,6 +3499,9 @@ get_lcid (const char *locale_name)
 # define LINGUISTIC_IGNORECASE  0x00000010
 #endif
 
+typedef int (WINAPI *CompareStringW_Proc)
+  (LCID, DWORD, LPCWSTR, int, LPCWSTR, int);
+
 int
 w32_compare_strings (const char *s1, const char *s2, char *locname,
 		     int ignore_case)
@@ -3507,7 +3510,7 @@ w32_compare_strings (const char *s1, const char *s2, char *locname,
   wchar_t *string1_w, *string2_w;
   int val, needed;
   extern BOOL g_b_init_compare_string_w;
-  static int (WINAPI *pCompareStringW)(LCID, DWORD, LPCWSTR, int, LPCWSTR, int);
+  static CompareStringW_Proc pCompareStringW;
   DWORD flags = 0;
 
   USE_SAFE_ALLOCA;
@@ -3523,8 +3526,9 @@ w32_compare_strings (const char *s1, const char *s2, char *locname,
     {
       if (os_subtype == OS_9X)
 	{
-	  pCompareStringW = GetProcAddress (LoadLibrary ("Unicows.dll"),
-					    "CompareStringW");
+	  pCompareStringW =
+            (CompareStringW_Proc) GetProcAddress (LoadLibrary ("Unicows.dll"),
+                                                  "CompareStringW");
 	  if (!pCompareStringW)
 	    {
 	      errno = EINVAL;