[PATCH] handle LIBS="" in test case 567

[Jeff Shimoda [Marbles504]]

Hello, another fix on z/OS Unix, this time for test case 567.  This
one happens to be very close to a problem reported in 2005 here:
https://lists.gnu.org/archive/html/bug-autoconf/2005-07/msg00018.html

I happen to be running into almost the same problem which is that on
z/OS Unix we are not setting the LIBS environment variable when
building/testing autoconf so on the first run of configure in test
567, LIBS="" appears in state-env.c-native.r1 but does not appear in
the second run of configure (which picks up the cache) in
state-env.c-native.r2.  When those two files are compared it results
in the test failing.  The fix back in 2005 was to add code to
tests/local.at to replace the single quotes in LIBS='' so the
comparison passes.  I would like to propose a similar fix which
replaces double quotes.

diff --git a/tests/local.at b/tests/local.at
index 7318f92..f303f81 100644
--- a/tests/local.at
+++ b/tests/local.at
@@ -482,6 +482,7 @@ do
   $SED '/^ac_cv_/ b skip
        /^m4_defn([m4_re_word])=./ !d
        /^[[^=]]*='\'''\''$/ d
+       /^[[^=]]*=""$/ d
        /^a[[cs]]_/ d
        : skip
        /^OLDPWD=/ d

-Jeff Shimoda