Mac OS X deployment target: piping opts through Makefiles

Makefile

 TOP=../..
 include $(TOP)/mk/boilerplate.mk
 
+# Beyond stage 1, honour any Mac OS X depolyment target options.  If we use 
+# these options in stage 1 we get a linker error if the bootstrap compiler is
+#  for a more recent OS version
+ifeq "$(stage)" "2"
+SRC_CC_OPTS += $(MACOSX_DEPLOYMENT_CC_OPTS)
+SRC_HC_OPTS += $(addprefix -optc, $(MACOSX_DEPLOYMENT_CC_OPTS))
+SRC_LD_OPTS += $(addprefix -optl, $(MACOSX_DEPLOYMENT_LD_OPTS))
+endif
+
 # We have two version: the inplace version compiled by the bootstrap compiler
 #   and the install version compiled by the stage 1 compiler
 ifeq "$(stage)" "2"