[NFC][tests] Replace use of GNUisms in usage of diff
authorHubert Tong <hubert.reinterpretcast@gmail.com>
Sun, 8 Nov 2020 17:05:29 +0000 (12:05 -0500)
committerHubert Tong <hubert.reinterpretcast@gmail.com>
Sun, 8 Nov 2020 17:07:51 +0000 (12:07 -0500)
commit09fc7796e57417071523c82bdac8b3bf050648a0
treee9a68f045fc550f0524570ddc919684f2c708d77
parent00808e321c724bd9f2a822bce87fe7fe87376371
[NFC][tests] Replace use of GNUisms in usage of diff

... the POSIX options suffice.

This maintains compatibility with the system `diff` on platforms
like AIX.
clang/test/APINotes/yaml-roundtrip-2.test
clang/test/APINotes/yaml-roundtrip.test