ci: add makefile of c samples

docs/examples/c/Makefile

@@ -0,0 +1,34 @@
+# Makefile for building TDengine examples on TD Linux platform
+
+INCLUDE_DIRS = 
+
+TARGETS = connect_example       \
+          create_db_demo        \
+          insert_data_demo      \
+          query_data_demo       \
+          with_reqid_demo       \
+          sml_insert_demo       \
+          stmt_insert_demo      \
+          tmq_demo
+
+SOURCES = connect_example.c     \
+          create_db_demo.c      \
+          insert_data_demo.c    \
+          query_data_demo.c     \
+          with_reqid_demo.c     \
+          sml_insert_demo.c     \
+          stmt_insert_demo.c    \
+          tmq_demo.c
+
+LIBS = -ltaos -lpthread
+
+
+CFLAGS = -g
+
+all: $(TARGETS)
+
+$(TARGETS):
+	$(CC) $(CFLAGS) -o $@ $(wildcard $(@F).c) $(LIBS)
+
+clean:
+	rm -f $(TARGETS)