mmap obmalloc arenas so that they may be immediately returned to the system when unused (closes #20494)
diff --git a/configure b/configure
index f865054..4bceec6 100755
--- a/configure
+++ b/configure
@@ -10164,7 +10164,7 @@
  clock confstr ctermid execv fchmod fchown fork fpathconf ftime ftruncate \
  gai_strerror getgroups getlogin getloadavg getpeername getpgid getpid \
  getpriority getresuid getresgid getpwent getspnam getspent getsid getwd \
- initgroups kill killpg lchmod lchown lstat mkfifo mknod mktime \
+ initgroups kill killpg lchmod lchown lstat mkfifo mknod mktime mmap \
  mremap nice pathconf pause plock poll pthread_init \
  putenv readlink realpath \
  select sem_open sem_timedwait sem_getvalue sem_unlink setegid seteuid \