build: sort llvm-readobj sources

Sort the source files.  NFC.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@209587 91177308-0d34-0410-b5e6-96231b3b80d8

tools/llvm-readobj/CMakeLists.txt

@@ -5,12 +5,12 @@ set(LLVM_LINK_COMPONENTS
   )
 
 add_llvm_tool(llvm-readobj
-  llvm-readobj.cpp
-  ObjDumper.cpp
+  ARMAttributeParser.cpp
   COFFDumper.cpp
   ELFDumper.cpp
-  MachODumper.cpp
   Error.cpp
+  llvm-readobj.cpp
+  MachODumper.cpp
+  ObjDumper.cpp
   StreamWriter.cpp
-  ARMAttributeParser.cpp
   )