API to enable log severity setting. (#30)

* The patch follows the discussion at this

ros2/rmw#124 url on rmw.

The patch enables setting log severity from userland applications. The parameter
passed is defined inside rmw/include/types.h

Signed-off-by: Sriram Raghunathan <sriram.max@gmail.com>

* Changing rmw_log_severity_t from const * to rmw_log_severity_t
addressing comments

Signed-off-by: Sriram Raghunathan <sriram.max@gmail.com>

rmw_implementation/src/functions.cpp

@@ -355,6 +355,10 @@ RMW_INTERFACE_FN(rmw_service_server_is_available,
   rmw_ret_t, RMW_RET_ERROR,
   3, ARG_TYPES(const rmw_node_t *, const rmw_client_t *, bool *))
 
+RMW_INTERFACE_FN(rmw_set_log_severity,
+  rmw_ret_t, RMW_RET_ERROR,
+  1, ARG_TYPES(rmw_log_severity_t))
+
 #define GET_SYMBOL(x) symbol_ ## x = get_symbol(#x);
 
 void prefetch_symbols(void)