Remove bin/podman.cross Make target

The local-cross Make target has superceeded this old Make target and the
warning to not use it has been in place now for 4+ years.

Removing it to clean up the Makefile slightly.

Signed-off-by: Lewis Roy <lewis@redhat.com>

Makefile

@@ -482,18 +482,6 @@ ifneq ($(GOOS),darwin)
 	$(GOCMD) generate ./pkg/bindings/... ;
 endif
 
-# DO NOT USE: use local-cross instead
-bin/podman.cross.%:
-	TARGET="$*"; \
-	GOOS="$${TARGET%%.*}"; \
-	GOARCH="$${TARGET##*.}"; \
-	CGO_ENABLED=0 \
-		$(GO) build \
-		$(BUILDFLAGS) \
-		$(GO_LDFLAGS) '$(LDFLAGS_PODMAN)' \
-		-tags '$(BUILDTAGS_CROSS)' \
-		-o "$@" ./cmd/podman
-
 .PHONY: local-cross
 local-cross: $(CROSS_BUILD_TARGETS) ## Cross compile podman binary for multiple architectures