one warning eliminated: sbrk() is not used

Author: Anton Leykin

M2/Macaulay2/d/types.h

@@ -141,10 +141,6 @@ struct JumpCell
 #endif
 #define RUP(x) ((((x) + PAGESIZE - 1) / PAGESIZE) * PAGESIZE)
 
-#if !defined(__FreeBSD__) && !defined(__DARWIN__)
-void *sbrk();		/* not really ansi standard, sigh */
-#endif
-
 #define STDIN 0
 #define STDOUT 1
 #define STDERR 2