Add support for MacOS on ARM

Also build with real -no-pie on ghactions, and fix SDL include directories (it's probably blind luck that they worked correctly on most systems).

cross-examples/macaa64.ini

@@ -0,0 +1,16 @@
+[built-in options]
+c_args = [ '-arch', 'arm64', '-mmacosx-version-min=10.15' ]
+cpp_args = [ '-arch', 'arm64', '-mmacosx-version-min=10.15' ]
+c_link_args = [ '-arch', 'arm64', '-mmacosx-version-min=10.15' ]
+cpp_link_args = [ '-arch', 'arm64', '-mmacosx-version-min=10.15' ]
+
+[binaries]
+c = 'clang'
+cpp = 'clang++'
+strip = 'strip'
+
+[host_machine]
+system = 'darwin'
+cpu_family = 'aarch64'
+cpu = 'armv8'
+endian = 'little'