sync_array_object_signalled(): Add a (void) cast to eliminate a gcc warning
about the return value of os_atomic_increment() being ignored.

rw_lock_create_func(): Properly indent the preprocessor directives.

rw_lock_x_lock_low(), rw_lock_x_lock_func_nowait(): Split lines correctly.

rw_lock_set_writer_id_and_recursion_flag(): Silence a Valgrind warning.
Do not mix statements and variable declarations.