[PATCH] - Use pool_strdup instead of STRDUP in the NSAPI plugin for PHP

The STRDUP macro in NSAPI ends up invoking pthread_get_specific each
time. Since the PHP NSAPI plugin has access to the pool member of the
Session variable, it can use pool_strdup instead of STRDUP.

Please review the attached patch that uses pool_strdup instead of
STRDUP thereby reducing the number of times pthread_getspecific is
invoked when the PHP engine is executing within Sun Web Server.

thanks,
arvi