configure: better check for the perl patch containing whitespace.

More for https://bugs.gnu.org/62896.

* configure.ac: quote "$PERL" and check directly with grep.

diff --git a/configure.ac b/configure.ac
index 23a9f97f540a64580f24a36b67d59b327b767288..946fecb675a22016cdf79d5b78f5a58b3ecfdce2 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -70,8 +70,8 @@ AC_PROG_LN_S
 AC_PATH_PROG([PERL], [perl])
 if test -z "$PERL"; then
    AC_MSG_ERROR([perl not found])
-elif test x"`echo $PERL | grep ' '`" != "x"; then
-  AC_MSG_ERROR([The path to your Perl contains spaces.
+elif echo "$PERL" | grep '[    ]' >/dev/null; then
+  AC_MSG_ERROR([The path to your Perl contains spaces or tabs.
 This would cause build failures later or unusable programs.
 Please use a path without spaces and try again.])
 fi