This reverts the r263125

It was discussed to make all messages be 
lowercase to be consistent with clang.
(also reverts the r263128 which fixed 
build bot fail after r263125)

Original commit message:
[ELF] - Consistent spelling for error/warning messages

Previously error and warnings were not consistent in lld.
Some of them started from lowercase letter, others from
uppercase. Also there was one or two which had a dot at the end.
This patch changes all messages to start from uppercase letter if
they were not before.

Differential revision: http://reviews.llvm.org/D18045

llvm-svn: 263240