mingw32: Enable C99/POSIX format strings

Starting with mingw32-runtime 3.15, C99/POSIX
format strings (%zu, %lld, ...) are supported
by defining __USE_MINGW_ANSI_STDIO=1.

As QEMU uses such format strings, unconditionally
define this macro. It won't hurt on older revisions
of mingw32-runtime.

Tested with manually installed mingw32-runtime 3.15
on debian (cross compiled + wine).
Signed-off-by: NStefan Weil <weil@mail.berlios.de>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

configure

@@ -441,6 +441,8 @@ fi
 if test "$mingw32" = "yes" ; then
   EXESUF=".exe"
   QEMU_CFLAGS="-DWIN32_LEAN_AND_MEAN -DWINVER=0x501 $QEMU_CFLAGS"
+  # enable C99/POSIX format strings (needs mingw32-runtime 3.15 or later)
+  QEMU_CFLAGS="-D__USE_MINGW_ANSI_STDIO=1 $QEMU_CFLAGS"
   LIBS="-lwinmm -lws2_32 -liphlpapi $LIBS"
 fi