Add RelocVisitor support for MachO

This commit adds partial support for MachO relocations to RelocVisitor.
A simple test case is added to show that relocations are indeed being
applied and that using llvm-dwarfdump on MachO files no longer errors.
Correctness is not yet tested, due to an unrelated bug in DebugInfo,
which will be fixed with appropriate testcase in a followup commit.

Differential Revision: http://reviews.llvm.org/D8148

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@238663 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Object/MachOObjectFile.cpp

@@ -1004,6 +1004,11 @@ std::error_code MachOObjectFile::getRelocationHidden(DataRefImpl Rel,
   return object_error::success;
 }
 
+uint8_t MachOObjectFile::getRelocationLength(DataRefImpl Rel) const {
+  MachO::any_relocation_info RE = getRelocation(Rel);
+  return getAnyRelocationLength(RE);
+}
+
 //
 // guessLibraryShortName() is passed a name of a dynamic library and returns a
 // guess on what the short name is.  Then name is returned as a substring of the