Fix installing ksh with dynamic libs on recent macOS (re: 41dfd03)

Problem: after 'sudo bin/package install /usr/local', the
dynamically linked /usr/local/bin/ksh binary will not find its
dynamic libraries in /usr/local/lib. Same for shcomp.

For macOS to find the dynamic libraries, we need dylink.sh to add
an "install name" of, e.g., @rpath/libshell.3.0.dylib instead of
simply libshell.3.0.dylib, and then at install time, we need to add
the directory path of the library (e.g., /usr/local/lib) to the
binary using install_name_tool(1).

Author: McDutchie

bin/package

@@ -2,7 +2,7 @@
 #                                                                      #
 #               This software is part of the ast package               #
 #          Copyright (c) 1994-2012 AT&T Intellectual Property          #
-#          Copyright (c) 2020-2025 Contributors to ksh 93u+m           #
+#          Copyright (c) 2020-2026 Contributors to ksh 93u+m           #
 #                      and is licensed under the                       #
 #                 Eclipse Public License, Version 2.0                  #
 #                                                                      #
@@ -136,7 +136,7 @@ case $(getopts '[-][123:xyz]' opt --xyz 2>/dev/null; echo 0$opt) in
 [-author?Glenn Fowler <gsf@research.att.com>]
 [-author?Contributors to https://github.com/ksh93/ksh]
 [-copyright?(c) 1994-2012 AT&T Intellectual Property]
-[-copyright?(c) 2020-2025 Contributors to ksh 93u+m]
+[-copyright?(c) 2020-2026 Contributors to ksh 93u+m]
 [-license?https://www.eclipse.org/org/documents/epl-2.0/EPL-2.0.html]
 [+NAME?'$command$' - build, test and install ksh 93u+m]
 [+DESCRIPTION?The \b'$command$'\b command is the main control script
@@ -568,7 +568,7 @@ IMPLEMENTATION
   author          Glenn Fowler <gsf@research.att.com>
   author          Contributors to https://github.com/ksh93/ksh
   copyright       (c) 1994-2012 AT&T Intellectual Property
-  copyright       (c) 2020-2025 Contributors to ksh 93u+m
+  copyright       (c) 2020-2026 Contributors to ksh 93u+m
   license         https://www.eclipse.org/org/documents/epl-2.0/EPL-2.0.html'
 		case $1 in
 		html)	echo "</pre></body></html>" ;;
@@ -2619,6 +2619,11 @@ do_install() # dir [ command ... ]
 		# install executable
 		if	test -f "dyn/bin/$f"
 		then	trace cp "dyn/bin/$f" "$bindir/" || exit
+			case $HOSTTYPE in
+			darwin.*)
+				trace install_name_tool -add_rpath "$libdir" "$bindir/$f" || exit
+				;;
+			esac
 		else	trace cp "bin/$f" "$bindir/" || exit
 		fi
 		# install manual pages and autoloadable functions

src/cmd/INIT/dylink.sh

@@ -1,7 +1,7 @@
 ########################################################################
 #                                                                      #
 #              This file is part of the ksh 93u+m package              #
-#          Copyright (c) 2021-2025 Contributors to ksh 93u+m           #
+#          Copyright (c) 2021-2026 Contributors to ksh 93u+m           #
 #                      and is licensed under the                       #
 #                 Eclipse Public License, Version 2.0                  #
 #                                                                      #
@@ -136,7 +136,7 @@ case ${exec_file} in
 	case $HOSTTYPE in
 	darwin.*)
 		do_link "lib/$lib_file" -dynamiclib \
-			-Wl,-dylib_install_name -Wl,"$lib_linkname" \
+			-Wl,-dylib_install_name -Wl,"@rpath/$lib_linkname" \
 			"$@" -L"$dest_dir/lib" $l_flags
 		;;
 	*)	do_link "lib/$lib_file" -shared -Wl,-soname -Wl,"$lib_linkname" \