Fixed ObjectFile functions:

- getSymbolOffset() renamed as getSymbolFileOffset()
- getSymbolFileOffset(), getSymbolAddress(), getRelocationAddress() returns same result for ELFObjectFile, MachOObjectFile and COFFObjectFile.
- added getRelocationOffset()
- fixed MachOObjectFile::getSymbolSize()
- fixed MachOObjectFile::getSymbolSection()
- fixed MachOObjectFile::getSymbolOffset() for symbols without section data.

llvm-svn: 145180