fix warning triggered when debugging on cygwin

diff --git a/tests/runtests.pl b/tests/runtests.pl
index 2660a4a..428e513 100755 (executable)
--- a/tests/runtests.pl
+++ b/tests/runtests.pl
@@ -97,6 +97,7 @@ use sshhelp qw(
     display_sshdlog
     display_sshlog
     display_sftplog
+    exe_ext
     find_sshd
     find_ssh
     find_sftp
@@ -133,7 +134,7 @@ my $SMTPPORT; # SMTP
 my $SMTP6PORT; # SMTP IPv6 server port
 
 my $srcdir = $ENV{'srcdir'} || '.';
-my $CURL="../src/curl"; # what curl executable to run on the tests
+my $CURL="../src/curl".exe_ext(); # what curl executable to run on the tests
 my $VCURL=$CURL;   # what curl binary to use to verify the servers with
                    # VCURL is handy to set to the system one when the one you
                    # just built hangs or crashes and thus prevent verification