MC: Clean up naming in MCObjectWriter. NFC.

MC: Clean up naming in MCObjectWriter. NFC.

s/WriteObject/writeObject/
s/RecordRelocation/recordRelocation/
s/IsSymbolRefDifferenceFullyResolved/isSymbolRefDifferenceFullyResolved/
s/Write8/write8/
s/WriteLE16/writeLE16/
s/WriteLE32/writeLE32/
s/WriteLE64/writeLE64/
s/WriteBE16/writeBE16/
s/WriteBE32/writeBE32/
s/WriteBE64/writeBE64/
s/Write16/write16/
s/Write32/write32/
s/Write64/write64/
s/WriteZeroes/writeZeroes/
s/WriteBytes/writeBytes/

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@239108 91177308-0d34-0410-b5e6-96231b3b80d8