darwin: add support for AppleM1 processor

rebar.config

@@ -29,6 +29,11 @@
     {"darwin10.*-32$", "CXXFLAGS", "-m32"},
     {"darwin10.*-32$", "LDFLAGS", "-arch i386"},
 
+    %% OSX M1 Apple silicon
+    {"aarch64-apple-darwin.*", "CFLAGS", "$CFLAGS -arch arm64"},
+    {"aarch64-apple-darwin.*", "CXXFLAGS", "$CXXFLAGS -arch arm64"},
+    {"aarch64-apple-darwin.*", "LDFLAGS", "-arch arm64"},
+
     {"win32", "CXXFLAGS", "$CXXFLAGS /O2 /DNDEBUG"}
 ]}.