* libc/sys/rtems/crt0.c (rtems_gxx_mutex_init): Dummy
routine to allow autoconf to determine that building executables
for rtems works.
(rtems_gxx_mutex_lock, rtems_gxx_mutex_unlock): Ditto.
(rtems_gxx_mutex_once): Ditto.
* libc/sys/rtems/crt0.c: Add stubs for functions implicitly
referenced by code generated by gcc 2.8.1.
(a29k): Add stubs for V_SPILL, V_FILL, V_BSD_OS, V_EPI_OS to
satisfy gcc.