fix -lto_library filtering for apple-clang + gfortran on sdk26 (#5474)

* ensure filter-out applies to subsequent sdk versions

Author: Chrismarsh

Makefile.system

@@ -441,7 +441,7 @@ ifeq (x$(XCVER), x 15)
 CCOMMON_OPT += -Wl,-ld_classic
 FCOMMON_OPT += -Wl,-ld_classic
 endif
-ifeq (x$(XCVER), x 16)
+ifeq ($(shell [ $(XCVER) -ge 16 ] && echo yes),yes)
 override CEXTRALIB := $(filter-out(-lto_library, $(CEXTRALIB))) 
 endif
 endif