[PATCH iproute2] build: Fix link errors on some systems

[Roi Dayan <roid@nvidia.com>]

Since moving get_rate() and get_size() from tc to lib, on some
systems we fail to link because of missing the math lib.
Move the link flag from tc makefile to the main makefile.

../lib/libutil.a(utils.o): In function `get_rate':
utils.c:(.text+0x10dc): undefined reference to `floor'
../lib/libutil.a(utils.o): In function `get_size':
utils.c:(.text+0x1394): undefined reference to `floor'
../lib/libutil.a(json_print.o): In function `sprint_size':
json_print.c:(.text+0x14c0): undefined reference to `rint'
json_print.c:(.text+0x14f4): undefined reference to `rint'
json_print.c:(.text+0x157c): undefined reference to `rint'

Fixes: f3be0e6366ac ("lib: Move get_rate(), get_rate64() from tc here")
Fixes: 44396bdfcc0a ("lib: Move get_size() from tc here")
Fixes: adbe5de96662 ("lib: Move sprint_size() from tc here, add print_size()")
Signed-off-by: Roi Dayan <roid@nvidia.com>
---
 Makefile    | 1 +
 tc/Makefile | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index e64c65992585..2a604ec58905 100644
--- a/Makefile
+++ b/Makefile
@@ -59,6 +59,7 @@ SUBDIRS=lib ip tc bridge misc netem genl tipc devlink rdma dcb man
 
 LIBNETLINK=../lib/libutil.a ../lib/libnetlink.a
 LDLIBS += $(LIBNETLINK)
+LDFLAGS += -lm
 
 all: config.mk
 	@set -e; \
diff --git a/tc/Makefile b/tc/Makefile
index 5a517af20b7c..8d91900716c1 100644
--- a/tc/Makefile
+++ b/tc/Makefile
@@ -110,7 +110,7 @@ ifneq ($(TC_CONFIG_NO_XT),y)
 endif
 
 TCOBJ += $(TCMODULES)
-LDLIBS += -L. -lm
+LDLIBS += -L.
 
 ifeq ($(SHARED_LIBS),y)
 LDLIBS += -ldl
-- 
1.8.3.1