Makefile.include/OSXNATIVE: refactor into _LINK

Refactor osx-native linker rule into `_LINK` too.

Makefile.include

@@ -321,7 +321,12 @@ LINKFLAGPREFIX ?= -Wl,
 
 DIRS += $(EXTERNAL_MODULE_DIRS)
 
-_LINK = $(if $(CPPMIX),$(LINKXX),$(LINK)) $(UNDEF) $(LINKFLAGPREFIX)--start-group $(BASELIBS) -lm $(LINKFLAGPREFIX)--end-group  $(LINKFLAGPREFIX)-Map=$(BINDIR)/$(APPLICATION).map $(LINKFLAGS)
+# Linker rule
+ifeq ($(BUILDOSXNATIVE),1)
+  _LINK = $(if $(CPPMIX),$(LINKXX),$(LINK)) $(UNDEF) $$(find $(BASELIBS) -size +8c) $(LINKFLAGS) $(LINKFLAGPREFIX)-no_pie
+else
+  _LINK = $(if $(CPPMIX),$(LINKXX),$(LINK)) $(UNDEF) $(LINKFLAGPREFIX)--start-group $(BASELIBS) -lm $(LINKFLAGPREFIX)--end-group $(LINKFLAGS) $(LINKFLAGPREFIX)-Map=$(BINDIR)/$(APPLICATION).map
+endif # BUILDOSXNATIVE
 
 ifeq ($(BUILD_IN_DOCKER),1)
 link: ..in-docker-container
@@ -330,11 +335,7 @@ else
 link: ..compiler-check ..build-message $(RIOTBUILD_CONFIG_HEADER_C) $(USEPKG:%=$(BINDIR)/%.a) $(APPDEPS)
 	$(Q)DIRS="$(DIRS)" "$(MAKE)" -C $(APPDIR) -f $(RIOTMAKE)/application.inc.mk
 ifeq (,$(RIOTNOLINK))
-ifeq ($(BUILDOSXNATIVE),1)
-	$(Q)$(if $(CPPMIX),$(LINKXX),$(LINK)) $(UNDEF) -o $(ELFFILE) $$(find $(BASELIBS) -size +8c) $(LINKFLAGS) $(LINKFLAGPREFIX)-no_pie
-else
 	$(Q)$(_LINK) -o $(ELFFILE)
-endif
 	$(Q)$(SIZE) $(ELFFILE)
 	$(Q)$(OBJCOPY) $(OFLAGS) $(ELFFILE) $(HEXFILE)
 endif