log: if log level is none drop all log functions

If disabling loging, don't compile in backend logging support which
bloats the object code.

Signed-off-by: William Roberts <william.c.roberts@intel.com>
diff --git a/src/util/log.c b/src/util/log.c
index 5d9da53..d2781f4 100644
--- a/src/util/log.c
+++ b/src/util/log.c
@@ -21,6 +21,8 @@
 #define unlikely(x)     (x)
 #endif
 
+#if MAXLOGLEVEL != LOGL_NONE
+
 static const char *log_strings[] = {
     "none",
     "(unused)",
@@ -254,3 +256,4 @@
     }
     return loglevel;
 }
+#endif