[X86] Remove uses of the -x86-experimental-vector-widening-legalization flag…

Authored by craig.topper on Aug 6 2019, 1:12 PM.


[X86] Remove uses of the -x86-experimental-vector-widening-legalization flag from test/CodeGen/X86/

This flag is now the default behavior so we no longer need to
set it in tests.

Some redundant tests have been removed after verifying we have
an equivalent test that didn't use the flag.

llvm-svn: 368079