General clean up of error handling in llvm-objdump to remove its use of report_fatal_error().

No real functional change with this commit.

The problem with report_fatal_error() is it does not include the tool name
and the file name the for which the error message was generated.

Uses of report_fatal_error() were change to report_error() or error()
to get a better error and to make the code smaller and cleaner.

Also changed things like error(errorToErrorCode(SOrErr.takeError())) to
use report_error() with a file name and the llvm::Error (as well as the
ArchitectureName if available) so the error message is printed.

llvm-svn: 287163