cache dump: do not try to unset BASH_ARGV/BASH_SOURCE

[Ralf Wildenhues]

While trying out automake/tests/instspc.test with recent Autoconf, I
noticed spurious errors about trying to unset BASH_ARGV.

Quoting bash 3.1 NEWS:
| This is a terse description of the new features added to bash-3.1 since
| the release of bash-3.0.  As always, the manual page (doc/bash.1) is
| the place to look for complete descriptions.
[...]
| b.  BASH_ARGC, BASH_ARGV, BASH_SOURCE, and BASH_LINENO are no longer created
|     as `invisible' variables and may not be unset.

This patch should avoid the error.  OK, or do you think this is
overkill?

Cheers,
Ralf

2006-11-27  Ralf Wildenhues  <address@hidden>

        * lib/autoconf/general.m4 (_AC_CACHE_DUMP): If `BASH_ARGV' or
        `BASH_SOURCE' contain a newline, set them to empty, as the may
        not be unset.

Index: lib/autoconf/general.m4
===================================================================
RCS file: /cvsroot/autoconf/autoconf/lib/autoconf/general.m4,v
retrieving revision 1.940
diff -u -r1.940 general.m4
--- lib/autoconf/general.m4     17 Nov 2006 21:04:54 -0000      1.940
+++ lib/autoconf/general.m4     27 Nov 2006 20:41:16 -0000
@@ -1821,6 +1821,7 @@
       esac
       case $ac_var in #(
       _ | IFS | as_nl) ;; #(
+      BASH_ARGV | BASH_SOURCE) eval $ac_var= ;; #(
       *) $as_unset $ac_var ;;
       esac ;;
     esac