Revert r298824 & r298816, recommit r298742 & r298754

r299989 fixes the underlying issue by waiting long enough to late parsed
arguments to be processed before doing an calculating the hash.

r298742
[ODRHash] Add error messages for mismatched parameters in methods.

r298754
[ODRHash] Add support for array and decayed types.

llvm-svn: 300001