Summary:
Currently, we report:
error: ...
Prepend argv[0] (tool name):
llvm-readobj: error: ...
This is consistent with most GNU binutils/clang/lld, and gives a bit
more context in a long build log.
Reviewed By: grimar, jhenderson, rupprecht
Differential Revision: https://reviews.llvm.org/D66425
llvm-svn: 369377
Fangrui Song