With this patch an undefined mask in a shufflevector will be printed as poison.
This change is done to support the new shufflevector semantics
for undefined mask elements.
Differential Revision: https://reviews.llvm.org/D149210
Change "negative" into "invalid" and put "invalid" at the beginning of
the file name, following the bulk of the invalid tests in the
SemaOpenCL directory.
Use the "invalid-" prefix only for tests that contain only invalid
constructs.
Drop the "valid" suffix for CodeGen tests, as inputs in this directory
are supposed to be valid anyway.