Our code style document says all our compile flags set by the build system should start LIBC_COPT_ but not all of them do. We should update them to fit our naming scheme.

Steps to fix:

1. go through the flags in config.json
2. For each flag, check what copt it defines
3. If that copt doesn't start with LIBC_COPT_, rename it so it does.
4. Make sure the flag is renamed everywhere it's used in code, cmake, and bazel.