This reverts commit 3229c97151.
With a2acac6 in place this should provide enough info to work out
any repeat of the failure in cross_ovver_uniform_dist.test.
Currently the UNSUPPORTED and XFAIL clauses support specifying
substrings of the target triple; but REQUIRES does not, which can trip
people up or lead to hacking config files to insert substitute feature
names. Consistency across all three lit clauses seems preferable.
Differential Revision: https://reviews.llvm.org/D107162