enable subs by default.

Former-commit-id: 42cea47bd66332eacf3c28083eca6ac048e64152

src/space.h

@@ -26,7 +26,7 @@
 #define space_splitratio                0.875f
 #define space_splitsize_default         400
 #define space_subsize_default           5000
-#define space_dosub                     0
+#define space_dosub                     1
 #define space_stretch                   1.05f
 #define space_maxtaskspercell           31
 #define space_maxreldx                  0.2f