Add header file to config_info.c for function definition.

src/api/config_info.c

@@ -30,6 +30,7 @@
 
 #include <errno.h>
 #include <stdio.h>
+#include <src/api/slurm.h>
 #include <src/common/slurm_protocol_api.h>
 
 /* slurm_print_ctl_conf - output the contents of Slurm's configuration message */