Do not pass -dynamic-linker to linker when !shared.
Fixes <http://bugs.gnu.org/20102>.

ARM 'link' spec issue reported at
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65711 and
https://gcc.gnu.org/ml/gcc-patches/2015-04/msg01387.html.

Patch by Ludovic Courtès <ludo@gnu.org>.

--- gcc-4.8.4/gcc/config/arm/linux-elf.h.orig	2015-04-08 20:31:20.376900478 +0200
+++ gcc-4.8.4/gcc/config/arm/linux-elf.h	2015-04-08 20:31:36.437014437 +0200
@@ -65,7 +65,7 @@
    %{symbolic:-Bsymbolic} \
    %{!static: \
      %{rdynamic:-export-dynamic} \
-     -dynamic-linker " GNU_USER_DYNAMIC_LINKER "} \
+     %{!shared:-dynamic-linker " GNU_USER_DYNAMIC_LINKER "}} \
    -X \
    %{mbig-endian:-EB} %{mlittle-endian:-EL}" \
    SUBTARGET_EXTRA_LINK_SPEC
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<tr><td><span title='2020-09-02 17:05:23 +0200'>2020-09-02</span></td><td><a href='/guix/commit/gnu/build/shepherd.scm?id=8ce6f4dc2879919c12bc76a2f4b01200af97e019'>installer: Run the installation inside a container.</a><span class='msg-avail'>...<span class='msg-tooltip'>When the store overlay is mounted, other processes such as kmscon, udev
and guix-daemon may open files from the store, preventing the
underlying install support from being umounted. See:
https://lists.gnu.org/archive/html/guix-devel/2018-12/msg00161.html.

To avoid this situation, mount the store overlay inside a container,
and run the installation from within that container.

* gnu/build/shepherd.scm (fork+exec-command/container): New procedure.
* gnu/services/base.scm (guix-shepherd-service): Support an optional PID
argument passed to the "start" method. If that argument is passed, ensure that
guix-daemon enters the given PID MNT namespace by using
fork+exec-command/container procedure.
* gnu/installer/final.scm (umount-cow-store): Remove it,
(install-system): run the installation from within a container.
* gnu/installer/newt/final.scm (run-install-shell): Remove the display hack.
</span></span></td><td>Mathieu Othacehe</td></tr>
<tr><td><span title='2020-06-12 00:04:42 +0200'>2020-06-12</span></td><td><a href='/guix/commit/gnu/build/shepherd.scm?id=8a02e45d93c2a825363da282791ac16f15b415e4'>shepherd: 'read-pid-file/container' terminates the whole process group.</a><span class='msg-avail'>...<span class='msg-tooltip'>This mirrors a change made in the Shepherd 0.8.0.  Previously, upon
startup failure, we could have left processes behind.

* gnu/build/shepherd.scm (read-pid-file/container): Kill (- PID) instead
of PID.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2020-06-12 00:04:42 +0200'>2020-06-12</span></td><td><a href='/guix/commit/gnu/build/shepherd.scm?id=b6b95685d0b478698d648f13afd927b1e1700d99'>shepherd: Unblock signals in the child process.</a><span class='msg-avail'>...<span class='msg-tooltip'>Fixes &lt;https://bugs.gnu.org/41791&gt;.
Reported by Tobias Geerinckx-Rice &lt;me@tobias.gr&gt;.

This change mirrors changes made in the Shepherd 0.8.1, where signals
are blocked in the shepherd process in support of 'signalfd'.  The
regression was introduced with the switch to 0.8.1 in
3f9c62d1a8b345909adaeb22f454ad22554c55a1: child processes would not
receive SIGTERM upon 'herd stop SERVICE'.

* gnu/build/shepherd.scm &lt;top level&gt;: Autoload (shepherd system).
(make-forkexec-constructor/container): Call call to 'sigaction' and
'unblock-signals'.
</span></span></td><td>Ludovic Courtès</td></tr>