protobuf_grpc: google serializing and RPC library

protobuf : 3.9.3
grpc     : 1.24.0

This a new version of the port with a vastly reduced port size.

Issue #190

recipes/api/grpc/content.mk

@@ -0,0 +1,22 @@
+content: include/grpc include/grpcpp lib/import/import-grpc.mk lib/symbols/grpc LICENSE
+
+PORT_DIR := $(call port_dir,$(REP_DIR)/ports/protobuf_grpc)
+
+include/grpc:
+	mkdir -p $@
+	cp -r $(PORT_DIR)/$@/* $@
+
+include/grpcpp:
+	mkdir -p $@
+	cp -r $(PORT_DIR)/$@/* $@
+
+lib/import/import-grpc.mk:
+	mkdir -p $(dir $@)
+	cp -a $(REP_DIR)/$@ $@
+
+lib/symbols/grpc:
+	mkdir -p $(dir $@)
+	cp -a $(REP_DIR)/$@ $@
+
+LICENSE:
+	cp $(PORT_DIR)/src/lib/grpc/LICENSE $@