When compiling media-gfx/enblend-4.1.1 with +openmp and +openexr, enblend bails during configure when trying to link with libvigraimpex. The problem is that libvigraimpex is installed, but linker complains that in one of the openexr libraries (I think libIlmThreads) some routines from pthreads are not defined. It appears that running CXXFLAGS=-lpthread emerge enblend solves the problem for me, but it would be great to know why it happened.
1) Please post your `emerge --info' output in a comment. 2) Please attach the entire build log to this bug report.