Detect ARM arch with variant when building (istio#15668)

* detect arm architecture

* remove hardcoded value

* only normalize arm with variant

Makefile

@@ -61,6 +61,10 @@ endif
 LOCAL_ARCH := $(shell uname -m)
 ifeq ($(LOCAL_ARCH),x86_64)
 GOARCH_LOCAL := amd64
+else ifeq ($(shell echo $(LOCAL_ARCH) | head -c 5),armv8)
+GOARCH_LOCAL := arm64
+else ifeq ($(shell echo $(LOCAL_ARCH) | head -c 4),armv)
+GOARCH_LOCAL := arm
 else
 GOARCH_LOCAL := $(LOCAL_ARCH)
 endif
@@ -355,11 +359,11 @@ DEBUG_LDFLAGS='-extldflags "-static"'
 # $(3): The value for LDFLAGS
 define genTargetsForNativeAndDocker
 $(ISTIO_OUT)/$(1):
-	STATIC=0 GOOS=$(GOOS) GOARCH=amd64 LDFLAGS=$(3) bin/gobuild.sh $(ISTIO_OUT)/$(1) $(2)
+	STATIC=0 GOOS=$(GOOS) GOARCH=$(GOARCH) LDFLAGS=$(3) bin/gobuild.sh $(ISTIO_OUT)/$(1) $(2)
 
 .PHONY: $(1)
 $(1):
-	STATIC=0 GOOS=$(GOOS) GOARCH=amd64 LDFLAGS=$(3) bin/gobuild.sh $(ISTIO_OUT)/$(1) $(2)
+	STATIC=0 GOOS=$(GOOS) GOARCH=$(GOARCH) LDFLAGS=$(3) bin/gobuild.sh $(ISTIO_OUT)/$(1) $(2)
 
 ifneq ($(ISTIO_OUT),$(ISTIO_OUT_LINUX))
 $(ISTIO_OUT_LINUX)/$(1):