[JDK-8346653] Add vzeroupper upon the entrance of AMD64 sha1 and sha256 stubs. #10353
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SHA-1 and SHA-256 instructions from the Intel SHA extensions (sha_ni) are SSE-based and may suffer from the performance penalty of SSE-AVX transition. This PR prepends vzeroupper to the AMD64 sha1 and sha256 stubs where these instructions are used. There is no need for inserting vzeroupper within the stub even though there may be AVX-encoded instructions, because these stubs only operate on the lower 128 bits. It addresses the performance issue described in #10275