imlib2 needs -lm

git-svn-id: file:///var/local/repositories/ffmpeg/trunk@3118 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

configure

@@ -853,7 +853,7 @@ int main( void ) { return (int) imlib_load_font("foo"); }
 EOF
 
 imlib2=no
-if $cc -o $TMPE $TMPC -lImlib2 > /dev/null 2>&1  ; then
+if $cc -o $TMPE $TMPC -lImlib2 -lm > /dev/null 2>&1  ; then
 imlib2=yes
 fi