[PATCH 4/6] tests: restore the tests on -Werror

[Akim Demaille]

When run as /bin/sh, Bash sets the shell variable POSIXLY_CORRECT to
y.  The test suite checks for the envvar POSIXLY_CORRECT to turn of
some tests not supported in POSIX mode.  Restore these tests.

Reported by the Hydra build farm, from Rob Vermaas.

* tests/local.at (AT_BISON_CHECK_WARNINGS_): Check the envvar
POSIXLY_CORRECT, not the shell variable.
---
 tests/local.at | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/tests/local.at b/tests/local.at
index 036b0a1..97107a5 100644
--- a/tests/local.at
+++ b/tests/local.at
@@ -462,10 +462,14 @@ m4_define([AT_BISON_CHECK_WARNINGS],
       [m4_null_if([$2], [AT_BISON_CHECK_WARNINGS_($@)])])])
 
 m4_define([AT_BISON_CHECK_WARNINGS_],
-[[# Defining POSIXLY_CORRECT causes bison to complain if options
-# are added after the grammar file name, so skip these checks
-# in that case.
-if test -z "${POSIXLY_CORRECT+set}"; then
+[[# Defining POSIXLY_CORRECT causes bison to complain if options are
+# added after the grammar file name, so skip these checks in that
+# case.
+#
+# Don't just check if $POSIXLY_CORRECT is set, as Bash, when launched
+# as /bin/sh, sets the shell variable POSIXLY_CORRECT to y, but not
+# the environment variable.
+if env | grep '^POSIXLY_CORRECT=' >/dev/null; then :; else
   ]AT_SAVE_SPECIAL_FILES[
 
   # To avoid expanding it repeatedly, store specified stdout.
-- 
1.7.12.2