Make sure to set TCLSH to an invocation of missing when it is not found. Fix...

Make sure to set TCLSH to an invocation of missing when it is not found.  Fix for the commit in #3196


git-svn-id: http://www.varnish-cache.org/svn/trunk/varnish-cache@3201 d4fa192b-c00b-0410-8231-f00ffab90ce4

configure.ac

@@ -219,7 +219,7 @@ else
 fi
 
 AM_MISSING_HAS_RUN
-AC_CHECK_PROGS(TCLSH, [tclsh tclsh8.4 tclsh8.5], false)
+AC_CHECK_PROGS(TCLSH, [tclsh tclsh8.4 tclsh8.5], :)
 if test "$TCLSH" = :; then
   TCLSH=${am_missing_run}tclsh
 fi