Merge pull request #3018 from martin-frbg/issue3015

Avoid concurrent inclusion of libgomp and libomp in clang+gfortran builds

Makefile

@@ -268,7 +268,11 @@ ifeq ($(NOFORTRAN), $(filter 0,$(NOFORTRAN)))
 	-@echo "POPTS       = $(LAPACK_FPFLAGS)" >> $(NETLIB_LAPACK_DIR)/make.inc
 	-@echo "FFLAGS_NOOPT       = -O0 $(LAPACK_NOOPT)" >> $(NETLIB_LAPACK_DIR)/make.inc
 	-@echo "PNOOPT      = $(LAPACK_FPFLAGS) -O0" >> $(NETLIB_LAPACK_DIR)/make.inc
+ifeq ($(C_COMPILER)$(F_COMPILER)$(USE_OPENMP), CLANGGFORTRAN1)
+	-@echo "LDFLAGS     = $(FFLAGS) $(EXTRALIB) -lomp" >> $(NETLIB_LAPACK_DIR)/make.inc
+else
 	-@echo "LDFLAGS     = $(FFLAGS) $(EXTRALIB)" >> $(NETLIB_LAPACK_DIR)/make.inc
+endif
 	-@echo "CC          = $(CC)" >> $(NETLIB_LAPACK_DIR)/make.inc
 	-@echo "override CFLAGS      = $(LAPACK_CFLAGS)" >> $(NETLIB_LAPACK_DIR)/make.inc
 	-@echo "AR          = $(AR)" >> $(NETLIB_LAPACK_DIR)/make.inc

f_check

@@ -330,6 +330,9 @@ if ($link ne "") {
 	    $flags =~ s/\@/\,/g;
 	    $linker_L .= "-Wl,". $flags . " " ;
 	}
+	if ($flags =~ /-lgomp/ && $CC =~ /clang/) {
+	    $flags = "-lomp";
+	}
 
 	if (
 	    ($flags =~ /^\-l/)