Order source files alphabetically in CMakeLists

Author: Dylan McKay

lib/Target/AVR/MCTargetDesc/CMakeLists.txt

@@ -1,11 +1,10 @@
 add_llvm_library(LLVMAVRDesc
   AVRAsmBackend.cpp
-  AVRMCAsmInfo.cpp
-  AVRMCCodeEmitter.cpp
-  AVRMCExpr.cpp
   AVRELFObjectWriter.cpp
   AVRELFStreamer.cpp
+  AVRMCAsmInfo.cpp
   AVRMCCodeEmitter.cpp
+  AVRMCExpr.cpp
   AVRMCTargetDesc.cpp
   AVRTargetStreamer.cpp
 )