Move virInterface related APIs out of libvirt.c

Introduce a src/libvirt-interface.c file to hold all the
methods related to the virInterface type.

docs/apibuild.py

@@ -25,6 +25,7 @@ included_files = {
   "virterror.h": "header with error specific API definitions",
   "libvirt.c": "Main interfaces for the libvirt library",
   "libvirt-domain-snapshot.c": "Domain snapshot interfaces for the libvirt library",
+  "libvirt-interface.c": "Interface interfaces for the libvirt library",
   "libvirt-network.c": "Network interfaces for the libvirt library",
   "virerror.c": "implements error handling and reporting code for libvirt",
   "virevent.c": "event loop for monitoring file handles",

src/Makefile.am

@@ -190,6 +190,7 @@ DRIVER_SOURCES =							\
 		$(NODE_INFO_SOURCES)					\
 		libvirt.c libvirt_internal.h				\
 		libvirt-domain-snapshot.c 				\
+		libvirt-interface.c	 				\
 		libvirt-network.c	 				\
 		locking/lock_manager.c locking/lock_manager.h		\
 		locking/lock_driver.h					\
@@ -2189,6 +2190,7 @@ libvirt_setuid_rpc_client_la_SOURCES = 		\
 		datatypes.c			\
 		libvirt.c			\
 		libvirt-domain-snapshot.c	\
+		libvirt-interface.c		\
 		libvirt-network.c		\
 		libvirt-lxc.c			\
 		$(NULL)