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)" \
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<tr><td><span title='2022-05-01 13:14:57 +0200'>2022-05-01</span></td><td><a href='/guix/commit/gnu/packages/coq.scm?id=556ccb4ae16562d200eeb00e4d22fc00fbee7959'>gnu: coq: Update to 8.15.1.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/coq.scm (coq): Update to 8.15.1.
</span></span></td><td>Julien Lepiller</td></tr>
<tr><td><span title='2022-02-11 10:36:39 +0100'>2022-02-11</span></td><td><a href='/guix/commit/gnu/packages/coq.scm?id=58ab579a9856eadb2acc4f2b47d3516734d0b6a4'>gnu: coq-stdpp: Update to 1.7.0.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/coq.scm (coq-stdpp): Update to 1.7.0.
</span></span></td><td>Julien Lepiller</td></tr>
<tr><td><span title='2022-02-11 10:33:17 +0100'>2022-02-11</span></td><td><a href='/guix/commit/gnu/packages/coq.scm?id=74a1e5378ae5ef9e4520120446991914a59d4744'>gnu: coq-mathcomp: Update to 1.14.0.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/coq.scm (coq-mathcomp): Update to 1.14.0.
</span></span></td><td>Julien Lepiller</td></tr>
<tr><td><span title='2022-02-11 10:32:56 +0100'>2022-02-11</span></td><td><a href='/guix/commit/gnu/packages/coq.scm?id=5179f4525d0859794b0d75ee1792d0f731d1f9c4'>gnu: coq: Update to 8.15.0.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/coq.scm (coq): Update to 8.15.0.
(coq-equations): Update to 1.3-8.15.
* gnu/packages/patches/coq-fix-envvars.patch: Adapt to new version.
</span></span></td><td>Julien Lepiller</td></tr>
<tr><td><span title='2022-02-11 10:32:53 +0100'>2022-02-11</span></td><td><a href='/guix/commit/gnu/packages/coq.scm?id=6b6474fec71c30a105e9d98f050b29a798b58a0b'>gnu: coq-interval: Update to 4.4.0.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/coq.scm (coq-interval): Update to 4.4.0.
</span></span></td><td>Julien Lepiller</td></tr>
<tr><td><span title='2022-02-11 10:32:50 +0100'>2022-02-11</span></td><td><a href='/guix/commit/gnu/packages/coq.scm?id=238a900baeea8df7d02081bd1fb46e1ba3be4eb5'>gnu: coq-bignums: Update to 8.15.0.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/coq.scm (coq-bignums): Update to 8.15.0.
</span></span></td><td>Julien Lepiller</td></tr>
<tr><td><span title='2022-02-11 10:32:47 +0100'>2022-02-11</span></td><td><a href='/guix/commit/gnu/packages/coq.scm?id=575c4ad510da2c66b38d4ee636b7cd717d5913d3'>gnu: coq-gappa: Update to 1.5.1.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/coq.scm (coq-gappa): Update to 1.5.1.
</span></span></td><td>Julien Lepiller</td></tr>
<tr><td><span title='2022-02-11 10:32:24 +0100'>2022-02-11</span></td><td><a href='/guix/commit/gnu/packages/coq.scm?id=8a338de2766588f3efffd2ee608c85ff7f6877a3'>gnu: coq-flocq: Update to 4.0.0.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/coq.scm (coq-flocq): Update to 4.0.0.
</span></span></td><td>Julien Lepiller</td></tr>
<tr><td><span title='2021-12-22 00:41:57 +0100'>2021-12-22</span></td><td><a href='/guix/commit/gnu/packages/coq.scm?id=bdf74dad1a337c2745c80ca94c662e9de0e7b8bb'>gnu: coq: Update to 8.14.1.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/coq.scm (coq-core): Update to 8.14.1.
</span></span></td><td>Julien Lepiller</td></tr>
<tr><td><span title='2021-12-13 17:48:25 +0100'>2021-12-13</span></td><td><a href='/guix/commit/gnu/packages/coq.scm?id=8394619baceb118df92e355377fd543bb1aa501a'>gnu: Simplify package inputs.</a><span class='msg-avail'>...<span class='msg-tooltip'>This commit was obtained by running:

  ./pre-inst-env guix style

without any additional argument.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2021-11-30 03:52:00 +0100'>2021-11-30</span></td><td><a href='/guix/commit/gnu/packages/coq.scm?id=d95a982cdd898790d247f013440f08a448265e3f'>gnu: coq: Update to 8.14.0.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/coq.scm (coq): Update to 8.14.0.
(coq-bignums): Update to 8.14.0.
(coq-equations): Update to 1.3.
* gnu/packages/patches/coq-fix-envvars.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.
</span></span></td><td>Julien Lepiller</td></tr>
<tr><td><span title='2021-11-30 03:19:33 +0100'>2021-11-30</span></td><td><a href='/guix/commit/gnu/packages/coq.scm?id=189501bf3b8facced98f08e73b7cdb83ec7a272b'>gnu: proof-general: Update to latest commit.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/coq.scm (proof-general): Update to latest commit.
[license]: Change to glp3+.
</span></span></td><td>Julien Lepiller</td></tr>
<tr><td><span title='2021-11-30 03:19:21 +0100'>2021-11-30</span></td><td><a href='/guix/commit/gnu/packages/coq.scm?id=bcd4c7ae6a8e8374cc75a5daf8e8b27138dc162f'>gnu: coq-semantics: Update to 8.14.0.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/coq.scm (coq-semantics): Update to 8.14.0.
</span></span></td><td>Julien Lepiller</td></tr>