[PHP-INTERNALS] TSRM mutex return value inconsitencies

Hi,

While doing some threaded work I noticed that tsrm_mutex_lock and
tsrm_mutex_unlock return different values for Windows and Linux (using
pthread).

Attached is the patch to make everything more pthread like, it will
return 0 for success and any other value is an error.

Windows, GNU Portable Threads and the NSAPI implementations were
returning incorrect values.

Scott