Remove elf specific info from ELFWriter.h to Elf.h. Code cleanup and more comments added

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@72982 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/ELFCodeEmitter.h b/lib/CodeGen/ELFCodeEmitter.h
index 7ea4d71..e9ee936 100644
--- a/lib/CodeGen/ELFCodeEmitter.h
+++ b/lib/CodeGen/ELFCodeEmitter.h
@@ -21,7 +21,7 @@
   class ELFCodeEmitter : public MachineCodeEmitter {
     ELFWriter &EW;
     TargetMachine &TM;
-    ELFWriter::ELFSection *ES;  // Section to write to.
+    ELFSection *ES;  // Section to write to.
     uint8_t *FnStartPtr;
   public:
     explicit ELFCodeEmitter(ELFWriter &ew) : EW(ew), TM(EW.TM) {}