This following patch was originally found at the debian mingw-w64 team's
binutils repo located here:
https://salsa.debian.org/mingw-w64-team/binutils-mingw-w64.git

Invoke the following in the aforementioned repo to see the original patch:

  $ git show da63f6b:debian/patches/reproducible-import-libraries.patch

Description: Make DLL import libraries reproducible
Author: Benjamin Moody <benjamin.moody@gmail.com>
Bug-Debian: https://bugs.debian.org/915055

--- a/ld/pe-dll.c
+++ b/ld/pe-dll.c
@@ -2844,6 +2844,7 @@
 
   bfd_set_format (outarch, bfd_archive);
   outarch->has_armap = 1;
+  outarch->flags |= BFD_DETERMINISTIC_OUTPUT;
 
   /* Work out a reasonable size of things to put onto one line.  */
   ar_head = make_head (outarch);
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<tr><td><span title='2020-06-27 23:42:20 +0200'>2020-06-27</span></td><td><a href='/guix/commit/tests/packages.scm?id=0505eda9c7cf688757f6f8be8bc3e65ad9f0805e'>packages: Recognize SHA3 and BLAKE2s for 'content-hash'.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2020-06-11 19:05:05 +0200'>2020-06-11</span></td><td><a href='/guix/commit/tests/packages.scm?id=03a70e4c190420e87c0b535285caf8f77260d4ff'>packages: 'package-grafts' returns grafts for all the relevant outputs.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2020-06-06 23:28:48 +0200'>2020-06-06</span></td><td><a href='/guix/commit/tests/packages.scm?id=b49caaa2b7f624c3395c8e872638282bcc420502'>packages: Make 'bag-grafts' insensitive to '%current-target-system'.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2020-05-23 16:29:29 +0200'>2020-05-23</span></td><td><a href='/guix/commit/tests/packages.scm?id=197c07a84767ac885ae2cf1300e0933efe424431'>tests: Use a #:prefix for (gcrypt hash).</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2020-05-22 01:29:39 +0200'>2020-05-22</span></td><td><a href='/guix/commit/tests/packages.scm?id=ce0be5675b702b2ff89aed1772ebb42af4150243'>packages: Introduce &lt;content-hash&gt; and use it in &lt;origin&gt;.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2020-05-14 17:21:27 +0200'>2020-05-14</span></td><td><a href='/guix/commit/tests/packages.scm?id=f52fbf7094c9c346d38ad469cc8d92d18387786e'>packages: Ensure bags are insensitive to '%current-target-system'.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2020-03-31 00:06:36 +0200'>2020-03-31</span></td><td><a href='/guix/commit/tests/packages.scm?id=a357849f5b1314c2a35efeee237645b9b08c39f5'>guix package: Do not misdiagnose upgrades when there are propagated inputs.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2020-03-31 00:06:36 +0200'>2020-03-31</span></td><td><a href='/guix/commit/tests/packages.scm?id=b9c79cae53f5f828e078ac5aafc2d80fa3204aae'>guix package: Add 'transaction-upgrade-entry' test.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2020-03-31 00:06:36 +0200'>2020-03-31</span></td><td><a href='/guix/commit/tests/packages.scm?id=a187cc562890895ad41dfad00eb1d5c4a4b00936'>guix package: 'transaction-upgrade-entry' swallows build requests.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2020-01-16 18:30:57 +0100'>2020-01-16</span></td><td><a href='/guix/commit/tests/packages.scm?id=84c5da08dda4fa8fd0e0f1e6a8a115190005f84a'>guix package: Export 'transaction-upgrade-entry'.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>