Make our architecture defines less stupid.

Our defines were never clear between what meant 64bit or x86_64
This makes a clear cut between bitness and architecture.
This commit also has the side effect of bringing up aarch64 compiling support.

Source/Core/Common/CMakeLists.txt

@@ -27,15 +27,14 @@ set(SRCS	BreakPoints.cpp
 			Crypto/bn.cpp
 			Crypto/ec.cpp)
 
-if(_M_ARM) #ARM
-	set(SRCS	${SRCS}
-				ArmCPUDetect.cpp
-				ArmEmitter.cpp)
+if(_M_ARM_32) #ARMv7
+	set(SRCS ${SRCS}
+	         ArmCPUDetect.cpp
+	         ArmEmitter.cpp)
 else()
-	if(NOT _M_GENERIC) #X86
-		set(SRCS	${SRCS}
-					x64FPURoundMode.cpp
-					)
+	if(_M_X86) #X86
+		set(SRCS ${SRCS}
+		         x64FPURoundMode.cpp)
 	endif()
 	set(SRCS ${SRCS} x64CPUDetect.cpp)
 endif()