[PATCH iproute2-next] devlink: Fix link errors on some systems

On some systems we fail to link because of missing math lib.
add -lm to devlink.

     LINK     devlink
../lib/libutil.a(utils_math.o): In function `get_rate':
utils_math.c:(.text+0xcc): undefined reference to `floor'
../lib/libutil.a(utils_math.o): In function `get_size':
utils_math.c:(.text+0x384): undefined reference to `floor'
collect2: error: ld returned 1 exit status
make[1]: *** [Makefile:16: devlink] Error 1
make: *** [Makefile:64: all] Error 2

Fixes: 6c70aca76ef2 ("devlink: Add port func rate support")
Signed-off-by: Roi Dayan <redacted>
---
  devlink/Makefile | 1 +
  1 file changed, 1 insertion(+)

diff --git a/devlink/Makefile b/devlink/Makefile
index d540feb3c012..d37a4b4d0241 100644
--- a/devlink/Makefile
+++ b/devlink/Makefile

@@ -7,6 +7,7 @@ ifeq ($(HAVE_MNL),y)
  
  DEVLINKOBJ = devlink.o mnlg.o
  TARGETS += devlink
+LDLIBS += -lm
  
  endif