[port] NetBSD and improper ctor for SpinLock fixes (#3092)

So when libc starts it has to start at an entry point located into crt0, now most OSes will do "enough" setup to allow mprotect() and mmap() to be called in static ctors (remember they're called BEFORE main)
By some stupid miracle, NetBSD doesn't; this means that using those functions on NetBSD will result in spurious results
The reason why is still unknown to me, but this is also combined with the fact that allocating a big chunk of memory for the JIT will make NetBSD refuse to mprotect()/mmap() it in low memory situations (even when space is available); so I take the same approach as with solaris
Also I now make it so fastmem handlers are NOT registered for OSes that disabled fastmem, this is because they pollute sigsegv and makes debugging stupidier

Signed-off-by: lizzie lizzie@eden-emu.dev

Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/3092
Reviewed-by: Caio Oliveira <caiooliveirafarias0@gmail.com>
Reviewed-by: MaranBr <maranbr@eden-emu.dev>
Co-authored-by: lizzie <lizzie@eden-emu.dev>
Co-committed-by: lizzie <lizzie@eden-emu.dev>

externals/CMakeLists.txt

@@ -27,7 +27,7 @@ set_directory_properties(PROPERTIES EXCLUDE_FROM_ALL ON)
 
 # Xbyak (also used by Dynarmic, so needs to be added first)
 if (ARCHITECTURE_x86 OR ARCHITECTURE_x86_64)
-    if (PLATFORM_SUN OR PLATFORM_OPENBSD)
+    if (PLATFORM_SUN OR PLATFORM_OPENBSD OR PLATFORM_NETBSD OR PLATFORM_DRAGONFLY)
         AddJsonPackage(xbyak_sun)
     else()
         AddJsonPackage(xbyak)