Move (actually copy) support for the sgi._getpty() function into
posix.openpty(). And conveniently also check if CVS write access really
works.

Closes SF patch #100722
diff --git a/configure b/configure
index 8293ee3..0418b84 100755
--- a/configure
+++ b/configure
@@ -1,6 +1,6 @@
 #! /bin/sh
 
-# From configure.in Revision: 1.136 
+# From configure.in Revision: 1.137 
 
 # Guess values for system-dependent variables and create Makefiles.
 # Generated automatically using autoconf version 2.13 
@@ -3645,7 +3645,7 @@
  setlocale setregid setreuid setsid setpgid setpgrp setuid setvbuf \
  sigaction siginterrupt sigrelse strftime strptime symlink sysconf \
  tcgetpgrp tcsetpgrp tempnam timegm times tmpfile tmpnam tmpnam_r \
- truncate uname waitpid
+ truncate uname waitpid _getpty
 do
 echo $ac_n "checking for $ac_func""... $ac_c" 1>&6
 echo "configure:3652: checking for $ac_func" >&5