Avoid linking both libgomp and libomp in mixed clang/gfortran builds

lapack-netlib/TESTING/EIG/CMakeLists.txt

@@ -107,6 +107,10 @@ set(ZDMDEIGTST zchkdmd.f90)
 macro(add_eig_executable name)
   add_executable(${name} ${ARGN})
   target_link_libraries(${name} openblas${SUFFIX64_UNDERSCORE})
+if (USE_OPENMP AND (${CMAKE_Fortran_COMPILER_ID} STREQUAL GNU) AND (${CMAKE_C_COMPILER_ID} STREQUAL Clang))
+	string(REGEX REPLACE "-fopenmp" "" CMAKE_Fortran_FLAGS "${CMAKE_Fortran_FLAGS}")
+target_link_libraries(${name} omp pthread)
+endif()
 #${TMGLIB} ../${LAPACK_LIBRARIES} ${BLAS_LIBRARIES})
 endmacro()