gh m1: fix mixed linkage when built with OpenMP and clang+gfortran

.github/workflows/apple_m.yml

@@ -102,6 +102,7 @@ jobs:
               mkdir build && cd build
               cmake -DDYNAMIC_ARCH=1 \
                     -DUSE_OPENMP=${{matrix.openmp}} \
+                    -DOpenMP_Fortran_LIB_NAMES=omp \
                     -DINTERFACE64=${{matrix.ilp64}} \
                     -DNOFORTRAN=0 \
                     -DBUILD_WITHOUT_LAPACK=0 \