Copy XCode15-specific workaround to Fortran flags to fix build of tests

Author: martin-frbg

Makefile.system

@@ -407,6 +407,7 @@ XCVER = $(shell pkgutil --pkg-info=com.apple.pkg.CLTools_Executables |awk '/vers
 endif
 ifeq (x$(XCVER), x 15)
 CCOMMON_OPT += -Wl,-ld_classic
+FCOMMON_OPT += -Wl,-ld_classic
 endif
 endif