Added workaround for AC_PROG_INSTALL being broken.

Needed for FreeBSD ports support.

Rev: src/configure.in:1.255

src/configure.in

-AC_REVISION("$Id: configure.in,v 1.254 1998/11/22 11:02:38 hubbe Exp $")
+AC_REVISION("$Id: configure.in,v 1.255 1998/12/03 03:16:05 grubba Exp $")
 AC_INIT(interpret.c)
 AC_CONFIG_HEADER(machine.h)
 
@@ -603,6 +603,15 @@ fi
 
 #############################################################################
 
+# The AC_PROG_INSTALL test is broken if $INSTALL is specified by hand.
+# The FreeBSD ports system does this...
+# Workaround:
+
+if test "x$INSTALL" = "x"; then :; else
+  # $INSTALL overrides ac_cv_path_install anyway...
+  ac_cv_path_install="$INSTALL"
+fi
+
 AC_PROG_INSTALL
 AC_PROG_CPP
 AC_PROG_RANLIB