Makefile: skip darwin/amd64 target

The darwin targets must be skipped for now as we don't have stable macOS
builders yet.

Change-Id: I017ef14451a0ac2cc815faec49d84ac47d66a192

Makefile

@@ -133,7 +133,7 @@ gateway_%:
 	$(MAKE) binary-check COMPONENT=gateway GOARCH=$(word 3, $(subst _, ,$@)) GOOS=$(word 2, $(subst _, ,$@))
 
 COMPONENTLIST := gateway
-OSARCHLIST    := darwin_amd64 linux_amd64 linux_arm linux_arm64 windows_amd64 freebsd_amd64
+OSARCHLIST    := linux_amd64 linux_arm linux_arm64 windows_amd64 freebsd_amd64
 BINARIES      := $(foreach C,$(COMPONENTLIST),$(foreach O,$(OSARCHLIST),$C_$O))
 .PHONY: binaries
 binaries: ${BINARIES} ## Build gateway binaries (jenkins)