simplify growproc

proc.c

@@ -49,16 +49,15 @@ allocproc(void)
 int
 growproc(int n)
 {
-  char *newmem, *oldmem;
+  char *newmem;
 
   newmem = kalloc(cp->sz + n);
   if(newmem == 0)
     return -1;
   memmove(newmem, cp->mem, cp->sz);
   memset(newmem + cp->sz, 0, n);
-  oldmem = cp->mem;
+  kfree(cp->mem, cp->sz);
   cp->mem = newmem;
-  kfree(oldmem, cp->sz);
   cp->sz += n;
   setupsegs(cp);
   return cp->sz - n;