clients: Include and link against math lib for new multi-resource

Linking failed with missing ceil() here. Making sure that we include
the header and add the missing -lm.

Signed-off-by: Stefan Schmidt <s.schmidt@samsung.com>

clients/Makefile.am

@@ -51,7 +51,7 @@ weston_multi_resource_SOURCES = multi-resource.c	\
 	../shared/os-compatibility.c			\
 	../shared/os-compatibility.h
 weston_multi_resource_CPPFLAGS = $(SIMPLE_CLIENT_CFLAGS)
-weston_multi_resource_LDADD = $(SIMPLE_CLIENT_LIBS)
+weston_multi_resource_LDADD = $(SIMPLE_CLIENT_LIBS) -lm
 endif
 
 if BUILD_SIMPLE_EGL_CLIENTS

clients/multi-resource.c

@@ -35,6 +35,7 @@
 #include <time.h>
 #include <sys/poll.h>
 #include <float.h>
+#include <math.h>
 
 #include <wayland-client.h>
 #include "../shared/os-compatibility.h"