mingw-w64-crt/stdio/mingw_pformat.c: Perform 64-bit comparison on the mantissa of a floating point number. This fixes #459.

Reference: https://sourceforge.net/p/mingw-w64/bugs/459/
Signed-off-by: Liu Hao <lh_mouse@126.com>
(cherry picked from commit 9cb3a1a9c6ccefd6c1b06c24402ca8cf3dd7b3b8)
Signed-off-by: Liu Hao <lh_mouse@126.com>

mingw-w64-crt/stdio/mingw_pformat.c

diff --git a/mingw-w64-crt/stdio/mingw_pformat.c b/mingw-w64-crt/stdio/mingw_pformat.c
index 1500aa3..24369d1 100644
--- a/mingw-w64-crt/stdio/mingw_pformat.c
+++ b/mingw-w64-crt/stdio/mingw_pformat.c
@@ -2036,8 +2036,8 @@
   {
     /* taking the rightmost digit in each pass...
      */
-    int c = value.__pformat_fpreg_mantissa & 0xF;
-    if( c == (int) value.__pformat_fpreg_mantissa)
+    unsigned c = value.__pformat_fpreg_mantissa & 0xF;
+    if( c == value.__pformat_fpreg_mantissa)
     {
       /* inserting the radix point, when we reach the last,
        * (i.e. the most significant digit), unless we found no