Revert "[DWARF] - Make collectAddressRanges() return section index in addition to Low/High PC"

Broked BB again:

TEST 'LLVM :: DebugInfo/X86/dbg-value-regmask-clobber.ll' FAILED
...
LLVM ERROR: Section was outside of section table.

llvm-svn: 303984

llvm/lib/Object/MachOObjectFile.cpp

@@ -1820,10 +1820,6 @@ uint64_t MachOObjectFile::getSectionAddress(DataRefImpl Sec) const {
   return getSection(Sec).addr;
 }
 
-uint64_t MachOObjectFile::getSectionIndex(DataRefImpl Sec) const {
-  return Sec.d.a;
-}
-
 uint64_t MachOObjectFile::getSectionSize(DataRefImpl Sec) const {
   // In the case if a malformed Mach-O file where the section offset is past
   // the end of the file or some part of the section size is past the end of