use the system malloc so we can easily
switch to others, like libumem. I'm not
entirely sure this should be changed upstream
yet.

--- tcsh-6.19.00/config_f.h.orig	Mon Sep 14 12:18:26 2015
+++ tcsh-6.19.00/config_f.h	Mon Sep 14 12:18:46 2015
@@ -135,7 +135,7 @@
  *		This can be much slower and no memory statistics will be
  *		provided.
  */
-#if defined(__MACHTEN__) || defined(PURIFY) || defined(MALLOC_TRACE) || defined(_OSD_POSIX) || defined(__MVS__) || defined (__CYGWIN__) || defined(__GLIBC__) || defined(__OpenBSD__) || defined(__APPLE__)
+#if defined(__MACHTEN__) || defined(PURIFY) || defined(MALLOC_TRACE) || defined(_OSD_POSIX) || defined(__MVS__) || defined (__CYGWIN__) || defined(__GLIBC__) || defined(__OpenBSD__) || defined(__APPLE__) || defined(SOLARIS2)
 # define SYSMALLOC
 #else
 # undef SYSMALLOC