iproute2 - Fix up and simplify variables pointing to install directories

Define where is the are located the iproute2 config files.
Get rid of trailing slashes for paths in several file.

Signed-off-by: Christoph J. Thompson <cjsthompson@gmail.com>
diff --git a/tc/tc_util.c b/tc/tc_util.c
index 36e3c7d..926ed08 100644
--- a/tc/tc_util.c
+++ b/tc/tc_util.c
@@ -25,7 +25,7 @@
 #include "tc_util.h"
 
 #ifndef LIBDIR
-#define LIBDIR "/usr/lib/"
+#define LIBDIR "/usr/lib"
 #endif
 
 const char *get_tc_lib(void)