Fix tablegen's PrintFatalError function to run registered file

cleanups.

Also, change code in tablegen which printed a message and then called
"exit(1)" to use PrintFatalError, instead.

This fixes instances where an empty output file was left behind after
a failed tablegen invocation, which would confuse subsequent ninja
runs into not attempting to rebuild.

Differential Revision: http://reviews.llvm.org/D9608

llvm-svn: 237058