Malloc cannot use pthread_mutex_init() to initialize a mutex because
the mutex initialization process does a malloc!
libc_r internals skip the malloc and assign an initializer to a static
structure and point the opaque type (pthread_mutex_t in this case) to
that structure. This is done on the assumption that the mutex will never
be destroyed. This style of initialization is only valid inside libc_r
because the structure that is assigned is opaque to the user.
This fix allows a simple program to get to main() again. 8-)
1a3a296d21