Optimize error handling for special cases.

This commit contains a few improvements:
1. Using a consequetive range of [0..4], will allow us to merge all
   branches of error_is_special into one comparison.
2. With (1), we can remove the for loops to find entries in
   error_status_map with a single O(1) lookup.
3. grpc_error_is_special() code paths should be inlined for ref
   and unref to avoid callq for the majority of cases where speical
   error is used.
4. grpc_error_get_int() should never accept a nullptr argument to
   avoid an expensive branch in the hot path. Callers should all
   allocate a dummy int on the stack when calling.

0 files changed, 0 insertions, 0 deletions