libtool automake android pthread

[greno]

When I try to build existing GNU toolchain projects 
using the Android and NDK sometimes I run into 
problems with pthread.  I get errors like this:
../../arm-linux-androideabi/bin/ld: cannot find -lpthread

Is there a switch to libtool to would ignore -lpthread 
if it is found since Android already has pthread?   

Or is there some conditional that could be added to 
configure.ac or automake that would test for Android 
and then we could use that conditional to 
conditionally set -lpthread in LD_FLAGS?

thx.