common.h: Convert some unnecessary variables to macros

common.h

@@ -11,9 +11,9 @@
  * has reserved less than minfree (in case of too little memory,
  * user takes precedence) and user does not have reserved more
  * than maxfree. */
-size_t static_minfree = 512*1048576UL;
-size_t static_maxfree = 2048*1048576UL;
-double split_ratio = 0.5;
+#define static_minfree (512*1048576UL)
+#define static_maxfree (2048*1048576UL)
+#define split_ratio 0.5
 
 /* Default nice value for processes started using compctl --run. */
 #define COMPNICE 12