MC: Use @IMGREL instead of @IMGREL32, which we can't parse

Nico Rieck added support for this 32-bit COFF relocation some time ago
for Win64 stuff. It appears that as an oversight, the assembly output
used "foo"@IMGREL32 instead of "foo"@IMGREL, which is what we can parse.

Sadly, there were actually tests that took in IMGREL and put out
IMGREL32, and we didn't notice the inconsistency. Oh well. Now LLVM can
assemble it's own output with slightly more fidelity.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218437 91177308-0d34-0410-b5e6-96231b3b80d8
[x86] Re-work a bunch of the v32i8 test cases to actually involve byte
shuffles rather than word shuffles.

As you might guess, these were built starting from the word shuffle test
cases and I failed to properly port a bunch of them and left them as
widened word shuffle test cases. We still have a couple of tests that
check our ability to widen shuffles, but now we will test the actual
byte shuffle quite a bit better.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218438 91177308-0d34-0410-b5e6-96231b3b80d8
[x86] More tweaks to the v32i8 test cases.

I made a mistake in the previous commit and produced the wrong pattern.
Fix that. Also make one more shuffle pattern byte-based rather than
word-based, and add two more blend patterns.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218439 91177308-0d34-0410-b5e6-96231b3b80d8