Suppress -Wshadow-compatible-local in folly/test/stl_tests/StlVectorTest.cpp
Suppress -Wshadow-compatible-local in folly/test/stl_tests/StlVectorTest.cpp

Summary:
[Folly] Suppress `-Wshadow-compatible-local` in `folly/test/stl_tests/StlVectorTest.cpp`.

That test source file is heavily macro-driven, and using `SCOPED_TRACE` repeatedly in macros can lead to violations of `-Wshadow-compatible-local`.

Reviewed By: meyering

Differential Revision: D7231029

fbshipit-source-id: 122e1d86032cf884a83ef1716fa48b8f4864a363

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