Fix a bug whereby 'mformat' could end up passing uninitialized bytes
to write(2).  This could be reproduced with:

  mformat -C -f 1440 -L 16  -N 77777777 -i  /tmp/x ::

where the output of /tmp/x would be non-deterministic.

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

--- mtools-4.0.23/mformat.c	2019-04-21 00:12:01.496116195 +0200
+++ mtools-4.0.23/mformat.c	2019-04-21 00:12:36.675967157 +0200
@@ -927,6 +927,7 @@ void mformat(int argc, char **argv, int
 	
 	char *endptr;
 
+	memset(&boot.bytes, '\0', sizeof boot);
 	hs = hs_set = 0;
 	argtracks = 0;
 	argheads = 0;

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<tr><td><span title='2021-12-13 17:48:25 +0100'>2021-12-13</span></td><td><a href='/guix/commit/gnu/packages/adns.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='2021-11-17 23:43:14 +0100'>2021-11-17</span></td><td><a href='/guix/commit/gnu/packages/adns.scm?id=3a317f7476f8c6012e166ff9f340f861938721c9'>Merge branch 'master' into core-updates-frozen</a></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2021-11-15 22:43:23 +0100'>2021-11-15</span></td><td><a href='/guix/commit/gnu/packages/adns.scm?id=ecbf59abad4e146a80ea2849d12569886bce732e'>gnu: Add c-ares-for-node.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/adns.scm (c-ares-for-node): New variable.

Co-authored-by: Marius Bakke &lt;marius@gnu.org&gt;
</span></span></td><td>Jelle Licht</td></tr>
<tr><td><span title='2021-10-18 14:37:26 +0000'>2021-10-18</span></td><td><a href='/guix/commit/gnu/packages/adns.scm?id=e486b2b674badc80627b11077b7df2ac1cab92d8'>Merge remote-tracking branch 'signed/master' into core-updates</a></td><td>Mathieu Othacehe</td></tr>
<tr><td><span title='2021-10-17 02:27:16 +0200'>2021-10-17</span></td><td><a href='/guix/commit/gnu/packages/adns.scm?id=a1030d215197148aa0b86b75edccb70884c3769f'>gnu: c-ares: Update to 1.17.2.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/adns.scm (c-ares/fixed): Update to 1.17.2.
</span></span></td><td>Tobias Geerinckx-Rice</td></tr>