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Defining __has_builtin to 0 for non-clang compilers in base headers can
lead to wrong detection of features. For example in base/location.h
checking for __has_builtin macros succeeds for non-clang compilers,
because base/check_op.h defines __has_builtin to 0 and is included
before base/location.h. Instead of defining __has_builtin to 0 for
non-clang compilers, define an independent preprocessor symbol that
reflects support for requested feature. Undefine the symbol to avoid
collision.

While we're at it fix base/memory/aligned_memory.h too.

Bug: 819294
Change-Id: Iac40dc44e7356b600e7d06aa4ccd1294bb09ebce
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2224252Reviewed-by: François Doray <fdoray@chromium.org>
Commit-Queue: François Doray <fdoray@chromium.org>
Cr-Commit-Position: refs/heads/master@{#773784}