Switch the OSX universal binary build to X86 + ARM64

This adds support for ARM64 and removes the support for i386.  Support for
i386 has been removed from XCode, and the building with this target fails
owing to missing libraries for this architecture.

Author: kroening

src/common

@@ -47,9 +47,9 @@ endif
 ifeq ($(filter-out OSX OSX_Universal,$(BUILD_ENV_)),)
   ifeq ($(BUILD_ENV_),OSX_Universal)
     # MacOS Fat Binaries
-    CP_CXXFLAGS += -force_cpusubtype_ALL -arch i386 -arch x86_64
-    CP_CFLAGS += -force_cpusubtype_ALL -arch i386 -arch x86_64
-    LINKFLAGS += -force_cpusubtype_ALL -arch i386 -arch x86_64
+    CP_CXXFLAGS += -force_cpusubtype_ALL -arch arm64 -arch x86_64
+    CP_CFLAGS += -force_cpusubtype_ALL -arch arm64 -arch x86_64
+    LINKFLAGS += -force_cpusubtype_ALL -arch arm64 -arch x86_64
   endif
   LINKLIB = /usr/bin/libtool -static -o $@ $^
   LINKBIN = $(CXX) $(LINKFLAGS) -o $@ $^ $(LIBS)