Fix PTHREAD_MUTEX_ADAPTIVE_NP and PTHREAD_MUTEX_ERRORCHECK_NP usage

The PTHREAD_MUTEX_ADAPTIVE_NP and PTHREAD_MUTEX_ERRORCHECK_NP are usually not defines, but enum values, so simple preprocessor check doesn't work.

Check for PTHREAD_MUTEX_ADAPTIVE_NP from the autoconf AS_COMPILE_IFELSE block and define HAVE_PTHREAD_MUTEX_ADAPTIVE_NP. This should enable adaptive mutex on Linux and FreeBSD.

As PTHREAD_MUTEX_ERRORCHECK actually comes from POSIX and Linux glibc does define it when compatibility macros are being set, we can just use PTHREAD_MUTEX_ERRORCHECK instead of PTHREAD_MUTEX_ERRORCHECK_NP.