import new drw from libsl and minor fixes.

- better scaling for occupied tag squares.
- draw statusline first to omitt some complicated calculations.

util.h

@@ -4,5 +4,5 @@
 #define MIN(A, B)               ((A) < (B) ? (A) : (B))
 #define BETWEEN(X, A, B)        ((A) <= (X) && (X) <= (B))
 
-void die(const char *errstr, ...);
-void *ecalloc(size_t, size_t);
+void die(const char *fmt, ...);
+void *ecalloc(size_t nmemb, size_t size);