Update MicroBlaze localplt.data.

This patch updates the MicroBlaze localplt.data based on the results
of a build with build-many-glibcs.py.  This is simply an empirical
update; quite possibly the port could be optimized to remove more
local PLT entry usage.

Tested (compilation tests) with build-many-glibcs.py.

	* sysdeps/unix/sysv/linux/microblaze/localplt.data (__pread64):
	Add libc.so PLT entry.
	(__tls_get_addr): Make ld.so PLT entry optional.