Skip this performance regression test.

The test measures things on the order of 20ms.  On a loaded machine, we
have seen enough variation that the test would fail.

--- grep-2.22/tests/long-pattern-perf	2016-01-03 12:52:38.491575007 +0100
+++ grep-2.22/tests/long-pattern-perf	2016-01-03 12:53:39.768464687 +0100
@@ -16,6 +16,7 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+exit 77
 . "${srcdir=.}/init.sh"; path_prepend_ ../src
 
 fail=0
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<tr><td><span title='2023-02-19 01:00:01 +0100'>2023-02-19</span></td><td><a href='/guix/commit/gnu/packages/aux-files/linux-libre/5.15-arm64.conf?id=e701f67246680c81dd111cf7136b936bf7d8718b'>gnu: linux-libre: Consistently provide the drop_monitor module.</a><span class='msg-avail'>...<span class='msg-tooltip'>This is needed by, e.g., &lt;https://github.com/nhorman/dropwatch&gt;.
Build it as a module everywhere for consistency.

* gnu/packages/aux-files/linux-libre/4.14-i686.conf:
Set CONFIG_NET_DROP_MONITOR=m.
* gnu/packages/aux-files/linux-libre/4.14-x86_64.conf: Likewise.
* gnu/packages/aux-files/linux-libre/4.19-i686.conf: Likewise.
* gnu/packages/aux-files/linux-libre/4.19-x86_64.conf: Likewise.
* gnu/packages/aux-files/linux-libre/5.10-arm.conf: Likewise.
* gnu/packages/aux-files/linux-libre/5.10-arm64.conf: Likewise.
* gnu/packages/aux-files/linux-libre/5.10-i686.conf: Likewise.
* gnu/packages/aux-files/linux-libre/5.10-x86_64.conf: Likewise.
* gnu/packages/aux-files/linux-libre/5.15-arm.conf: Likewise.
* gnu/packages/aux-files/linux-libre/5.15-arm64.conf: Likewise.
* gnu/packages/aux-files/linux-libre/5.15-i686.conf: Likewise.
* gnu/packages/aux-files/linux-libre/5.15-x86_64.conf: Likewise.
* gnu/packages/aux-files/linux-libre/5.4-arm.conf: Likewise.
* gnu/packages/aux-files/linux-libre/5.4-arm64.conf: Likewise.
* gnu/packages/aux-files/linux-libre/5.4-i686.conf: Likewise.
* gnu/packages/aux-files/linux-libre/5.4-x86_64.conf: Likewise.
* gnu/packages/aux-files/linux-libre/6.1-arm.conf: Likewise.
* gnu/packages/aux-files/linux-libre/6.1-arm64.conf: Likewise.
* gnu/packages/aux-files/linux-libre/6.1-i686.conf: Likewise.
* gnu/packages/aux-files/linux-libre/6.1-x86_64.conf: Likewise.

Reported by mirai in #guix.
</span></span></td><td>Tobias Geerinckx-Rice</td></tr>