[llvm-objdump] - Cleanup the code. NFCI.

This is a cosmetic cleanup for the llvm-objdump code.

This patch:
* Renames things to match the official LLVM code style (lower case -> upper case).
* Removes few obviously excessive variables.
* Moves a few lines closer to the place of use, reorders the code a bit to simplify it,
to avoid doing excessive returns and to avoid using 'else` after returns.

I focused only on a llvm-objdump.h/llvm-objdump.cpp files. Few changes in the
MachODump.cpp and COFFDump.cpp are a result of llvm-objdump.h modification.

Differential revision: https://reviews.llvm.org/D56637

llvm-svn: 351171
diff --git a/llvm/tools/llvm-objdump/COFFDump.cpp b/llvm/tools/llvm-objdump/COFFDump.cpp
index a7ee495..55607ec 100644
--- a/llvm/tools/llvm-objdump/COFFDump.cpp
+++ b/llvm/tools/llvm-objdump/COFFDump.cpp
@@ -455,7 +455,7 @@
       Rels.push_back(Reloc);
 
     // Sort relocations by address.
-    llvm::sort(Rels, RelocAddressLess);
+    llvm::sort(Rels, isRelocAddressLess);
 
     ArrayRef<uint8_t> Contents;
     error(Obj->getSectionContents(Pdata, Contents));