Rename STR_IS_SHARED_M to STR_BORROWED
Since the introduction of STR_SHARED_ROOT, the word "shared" has become very overloaded with respect to String's internal states. Use a different name for STR_IS_SHARED_M and explain its purpose.
Added by alanwu (Alan Wu) about 6 years ago
Rename STR_IS_SHARED_M to STR_BORROWED
Since the introduction of STR_SHARED_ROOT, the word "shared"
has become very overloaded with respect to String's internal
states. Use a different name for STR_IS_SHARED_M and explain
its purpose.