[win64] Add the mingw64 prefix currently in vogue on the mingw64 installation guide.

[Jeremy White]

---
 aclocal.m4 |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/aclocal.m4 b/aclocal.m4
index f7beb5d..0736a8a 100644
--- a/aclocal.m4
+++ b/aclocal.m4
@@ -142,7 +142,7 @@ dnl
 AC_DEFUN([WINE_CHECK_MINGW_PROG],
 [AC_CHECK_PROGS([$1],
    m4_foreach([ac_wine_prefix],
-              [$host_cpu-pc-mingw32, i586-mingw32msvc, i386-mingw32msvc, i686-mingw32, i586-mingw32, i486-mingw32, i386-mingw32, i686-pc-mingw32],
+              [$host_cpu-w64-mingw32, $host_cpu-pc-mingw32, i586-mingw32msvc, i386-mingw32msvc, i686-mingw32, i586-mingw32, i486-mingw32, i386-mingw32, i686-pc-mingw32],
               [ac_wine_prefix-$2 ]),
    [$3],[$4])])