configurator failed under clang:
checking for #pragma omp and -fopenmp support... ccan/tools/configurator/configurator: Test for HAVE_OPENMP failed with 32512:
./configurator.out: error while loading shared libraries: libomp.so: cannot open shared object file: No such file or directory
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>