vapi: implement vapi_wait() for reads

Type: improvement

The function vapi_wait() is intended to allow a caller to block while
waiting until the API queue can be read/written. It was a stub that
returned VAPI_ENOTSUP. Add code which implements the wait on being able
to read an incoming message.

Had to touch a few other things in vapi.h to make checkstyle.sh happy
after changing the prototype of vapi_wait().

Signed-off-by: Matthew Smith <mgsmith@netgate.com>
Change-Id: Ida80c1a1d34fe297ab23268087be65ea53ad7040
diff --git a/src/vpp-api/vapi/vapi.c b/src/vpp-api/vapi/vapi.c
index 7808bec..25571dc 100644
--- a/src/vpp-api/vapi/vapi.c
+++ b/src/vpp-api/vapi/vapi.c
@@ -989,9 +989,13 @@
 }
 
 vapi_error_e
-vapi_wait (vapi_ctx_t ctx, vapi_wait_mode_e mode)
+vapi_wait (vapi_ctx_t ctx)
 {
-  return VAPI_ENOTSUP;
+  svm_queue_lock (ctx->vl_input_queue);
+  svm_queue_wait (ctx->vl_input_queue);
+  svm_queue_unlock (ctx->vl_input_queue);
+
+  return VAPI_OK;
 }
 
 static vapi_error_e