Having libc_errno outside of the namespace causes versioning issues when
trying to link the tests against LLVM-libc. Most of this patch is just
moving libc_errno inside the namespace in tests. This isn't necessary in
the function implementations since those are already inside the
namespace.
PR 79573 introduced `ASSERT_ERRNO_*` macros for use in libc tests.
Introduce these macro definitions to FuchsiaTest.h for string tests to
compile on Fuchsia.
The Fuchsia zxtest library has ASSERT_DEATH but not EXPECT_DEATH.
The latter may be added in the future, but for now just use the
former as substitute.
Reviewed By: abrachet
Differential Revision: https://reviews.llvm.org/D156940
This part of the effort to make all test related pieces into the `test`
directory. This helps is excluding test related pieces in a straight
forward manner if LLVM_INCLUDE_TESTS is OFF. Future patches will also move
the MPFR wrapper and testutils into the 'test' directory.
