Add mg_ prefix to mongoose sources

CL: none

PUBLISHED_FROM=d6ebe5fa88c61ae3b8569897d9b09d54610bec73

docs/c-api/intro.md

@@ -1,16 +0,0 @@
----
-items:
-  - { name: mbuf.h }
-  - { name: net.h }
-  - { name: http.h }
-  - { name: http_server.h }
-  - { name: http_client.h }
-  - { name: dns.h }
-  - { name: dns_server.h }
-  - { name: resolv.h }
-  - { name: mqtt.h }
-  - { name: mqtt_server.h }
-  - { name: coap.h }
-  - { name: util.h }
-  - { name: uri.h }
----