[X86][SSE] Added tests for insertion of zero elements into vectors
[X86][SSE] Added tests for insertion of zero elements into vectors

Many of these could be much better if we just lowered them all as shuffles - especially for the 256-bit vectors.

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@256708 91177308-0d34-0410-b5e6-96231b3b80d8

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