BF: install_yn is currently 'lost' between shell commands

The current tclinstall rule looks to be failing due to install_yn not being propagated between shell commands. This breaks the test that runs auto_mkindex, example output from a make install below

Installing tcl scripts
install -p -m 0755 feat.tcl <blah>/tcl/
...
ln -s Runtcl Feat_gui
...
/bin/sh: line 0: [: =: unary operator expected

config/rules.mk

@@ -156,13 +156,13 @@ tclinstall:
 		fi \
 	done
 	@# index installed TCL files
-	@install_yn=no;
-	@for tclfile in ${TCLFILES} verylongdummyname ; do \
+	@install_yn=no; \
+	for tclfile in ${TCLFILES} verylongdummyname ; do \
 		if [ -e $$tclfile ] ; then \
 			install_yn=yes; \
 		fi; \
-	done;
-	@if [ $$install_yn = "yes" ] ; then \
+	done; \
+	if [ $$install_yn = "yes" ] ; then \
 		(cd ${dest_TCLDIR} ; echo 'auto_mkindex . *.tcl' | ${TCLSH} ) \
 	fi