Install everything in PREFIX, set EXTRA_PATH to find it there.

--- ./Makefile.in~	2016-02-06 01:29:16.595090365 +0100
+++ ./Makefile.in	2016-02-06 09:29:04.286008931 +0100
@@ -133,9 +133,9 @@
 # require for testing here (like TCLX_LIBRARY).
 #========================================================================

-EXTRA_PATH	= $(top_builddir):$(TCL_BIN_DIR)
+EXTRA_PATH	= $(top_builddir):$(TCL_BIN_DIR):$(libdir)
 #EXTRA_PATH     = $(top_builddir):$(TCL_BIN_DIR):$(TK_BIN_DIR)
-TCLLIBPATH      = $(top_builddir)
+TCLLIBPATH      = $(pkglibdir)
 TCLSH_ENV	= TCL_LIBRARY=`@CYGPATH@ $(TCL_SRC_DIR)/library` \
 		  @LD_LIBRARY_PATH_VAR@="$(EXTRA_PATH):$(@LD_LIBRARY_PATH_VAR@)" \
 		  PATH="$(EXTRA_PATH):$(PATH)" \
 ption value='koszko' selected='selected'>koszko</option>
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<tr><td><span title='2020-03-06 20:50:18 +0000'>2020-03-06</span></td><td><a href='/guix/commit/po/doc/local.mk?id=895e6e8af657d28527f7cccf68eab7319f50fba5'>doc: Fix build of German Cookbook translation.</a><span class='msg-avail'>...</span></td><td>Florian Pelz</td></tr>
<tr><td><span title='2020-02-17 06:52:11 +0000'>2020-02-17</span></td><td><a href='/guix/commit/po/doc/local.mk?id=f98e83a17fa30587520e858231ec9c61f3624ecd'>doc: Add German Cookbook translation.</a><span class='msg-avail'>...</span></td><td>Florian Pelz</td></tr>
<tr><td><span title='2019-09-18 11:38:14 +0200'>2019-09-18</span></td><td><a href='/guix/commit/po/doc/local.mk?id=7bc46ecc34ceb042ff890e5d306d0a2a736e891d'>doc: Add Guix Cookbook.</a><span class='msg-avail'>...</span></td><td>Ricardo Wurmus</td></tr>
<tr><td><span title='2019-05-13 10:46:03 +0200'>2019-05-13</span></td><td><a href='/guix/commit/po/doc/local.mk?id=3bac7e6495934de9913e6186d954d1331883e064'>doc: Add Russian translation.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2019-04-30 18:11:15 +0200'>2019-04-30</span></td><td><a href='/guix/commit/po/doc/local.mk?id=81824af6a4b30368ed497686976c26f742bc6c8a'>build: 'guix-manual.*.po' no longer depends on 'guix-manual.pot'.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2019-04-29 22:21:14 +0200'>2019-04-29</span></td><td><a href='/guix/commit/po/doc/local.mk?id=842a687264e4dd88e4aa7f608582d6adc0313a07'>maint: Mark 'doc-pot-update' and 'doc-po-update' as phony.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>