devel/bullet: fix build on powerpc

: && /usr/bin/c++ -fPIC -O2 -pipe -fstack-protector-strong -fno-strict-aliasing -std=c++11 -fopenmp -O2 -pipe -fstack-protector-strong -fno-strict-aliasing -fstack-protector-strong -shared -Wl,-soname,libHACD.so.3.20 -o Extras/HACD/libHACD.so.3.20 Extras/HACD/CMakeFiles/HACD.dir/hacdGraph.o Extras/HACD/CMakeFiles/HACD.dir/hacdHACD.o Extras/HACD/CMakeFiles/HACD.dir/hacdICHull.o Extras/HACD/CMakeFiles/HACD.dir/hacdManifoldMesh.o -pthread && :
ld: error: unable to find library -lomp