Fix typos: (re)?sor?uce -> (re)?source

Closes: https://github.com/llvm/llvm-project/pull/10



In-collaboration-with:	Olivier Cochard-Labbé <olivier@FreeBSD.org>
Signed-off-by: Enji Cooper <yaneurabeya@gmail.com>

Differential Revision: https://reviews.llvm.org/D61021

llvm-svn: 359277