[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

Author: topperc

llvm/test/CodeGen/X86/SwizzleShuff.ll

@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
-; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mattr=+avx -x86-experimental-vector-widening-legalization | FileCheck %s
+; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mattr=+avx | FileCheck %s
 
 ; Check that we perform a scalar XOR on i32.