build: fixed clang's warning when building openssl.
clang doesn't seem to support 'Wno-old-style-declaration', this is a work-around.
Fixes: https://github.com/nodejs/node/issues/25550 Refs: https://github.com/nodejs/node-v0.x-archive/issues/4186
Checklist
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make -j4 test
(UNIX), orvcbuild test
(Windows) passes -
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