configure.ac: Don't look for pthreads in Android platform

In Android, the pthreads libs are in bionic.  When building
Mesa for Android with the autotools workflow, we shouldn't
set -lpthread or -pthread.

[Emil Velikov]
Other platforms could use a similar fix, although that is left as
separate exercise.

Reviewed-by: Emil Velikov <emil.velikov@collabora.com>
1 file changed