[libc++] Add assertions on OOB accesses in std::array when the debug mode is enabled

Like we do for empty std::array, make sure we have assertions in place
for obvious out-of-bounds issues in std::array when the debug mode is
enabled (which isn't by default).

Cr-Mirrored-From: https://chromium.googlesource.com/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: 23776a178f8379e1d9b4d79952bac916c1fa70fe
1 file changed