WoA: skip <sys/mman.h> on Windows ARM64 in ARM JIT support (refs #1991)

compemu_support_arm.cpp unconditionally includes <sys/mman.h> for
aarch64 before sysconfig.h is processed, so even with USE_JIT=OFF
(AMIBERRY_NO_JIT defined) the include is still attempted. Windows
has no POSIX mman header, so the build fails with 'sys/mman.h' not
found.

Narrow the guard to '!defined(_WIN32)'. On WoA the rest of the file
is already elided by '#if defined(JIT)' at line 49, so this leaves
an empty translation unit — which is what we want for Phase 1.

Author: midwan

src/jit/arm/compemu_support_arm.cpp

@@ -31,7 +31,7 @@
 #include "sysdeps.h"
 
 #include <math.h>
-#if defined(CPU_AARCH64)
+#if defined(CPU_AARCH64) && !defined(_WIN32)
 #include <sys/mman.h>
 #endif