w64: Use larger alignment for section with generated code

The MinGW-w64 compiler allows __attribute__((aligned (32)).

Signed-off-by: Stefan Weil <sw@weilnetz.de>

exec.c

diff --git a/exec.c b/exec.c
index 3dda2ca..6d10595 100644
--- a/exec.c
+++ b/exec.c
@@ -93,8 +93,7 @@
 #define code_gen_section                                \
     __attribute__((__section__(".gen_code")))           \
     __attribute__((aligned (32)))
-#elif defined(_WIN32)
-/* Maximum alignment for Win32 is 16. */
+#elif defined(_WIN32) && !defined(_WIN64)
 #define code_gen_section                                \
     __attribute__((aligned (16)))
 #else