Replace direct uses of implementation-specific rwlock functions in
lib/isc/include/isc/rwlock.h with preprocessor macros that use
ERRNO_CHECK(), in order to augment rwlock-related error messages with
file/line/caller information and the error string corresponding to
errno. Adjust the implementation-specific functions for pthreads-based
rwlocks so that they return any errors encountered to the caller instead
of aborting execution immediately using RUNTIME_CHECK().
To keep code modifications simple, make the non-pthreads-based
implementation-specific rwlock functions always return 0; these
functions continue to handle errors using less verbose run-time
assertions as they do not set errno anyway.
Michał Kępień
56638c94b5