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

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

  $ git show 4974e2c:debian/patches/dlltool-temp-prefix.patch

Description: Specify dlltool's temp prefix
Author: Stephen Kitt <steve@sk2.org>

By default dlltool uses its pid for the object files it generates.
Enforcing its temp prefix allows the files it generates to be
reproducible.

--- a/mingw-w64-crt/Makefile.am
+++ b/mingw-w64-crt/Makefile.am
@@ -36,7 +36,7 @@
   DTDEF32=$(GENLIB) $(DLLTOOLFLAGS32) $(AM_DLLTOOLFLAGS)
   DTDEF64=$(GENLIB) $(DLLTOOLFLAGS64) $(AM_DLLTOOLFLAGS)
 else
-  AM_DLLTOOLFLAGS=-k --as=$(AS) --output-lib $@
+  AM_DLLTOOLFLAGS=-k --as=$(AS) --output-lib $@ --temp-prefix $$(basename $@ .a)
   DLLTOOLFLAGSARM32=-m arm
   DLLTOOLFLAGSARM64=-m arm64
   DLLTOOLFLAGS32=--as-flags=--32 -m i386
'></td></tr></table>
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<div class='path'>path: <a href='/guix/log/?id=6ff3c33a0ee40afecc523809edeaa23ede9b2d74'>root</a>/<a href='/guix/log/nix?id=6ff3c33a0ee40afecc523809edeaa23ede9b2d74'>nix</a>/<a href='/guix/log/nix/libutil?id=6ff3c33a0ee40afecc523809edeaa23ede9b2d74'>libutil</a>/<a href='/guix/log/nix/libutil/util.hh?id=6ff3c33a0ee40afecc523809edeaa23ede9b2d74'>util.hh</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/nix/libutil/util.hh?id=6ff3c33a0ee40afecc523809edeaa23ede9b2d74&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2020-12-08 22:30:07 +0100'>2020-12-08</span></td><td><a href='/guix/commit/nix/libutil/util.hh?id=2e308238ad09e9527f9b8c3ec4a90b6b05a93367'>daemon: 'Agent' constructor takes a list of environment variables.</a><span class='msg-avail'>...<span class='msg-tooltip'>* nix/libutil/util.hh (struct Agent)[Agent]: Add 'env' parameter.
* nix/libutil/util.cc (Agent::Agent): Honor it.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2020-09-14 15:42:55 +0200'>2020-09-14</span></td><td><a href='/guix/commit/nix/libutil/util.hh?id=ee9dff34f9317509cb2b833d07a0d5e01a36a4ae'>daemon: Move 'Agent' to libutil.</a><span class='msg-avail'>...<span class='msg-tooltip'>* nix/libstore/build.cc (DerivationGoal::tryBuildHook): Add "offload" to
'args' and pass settings.guixProgram as the first argument to
Agent::Agent.
(pathNullDevice, commonChildInit, Agent, Agent::Agent)
(Agent::~Agent): Move to...
* nix/libutil/util.cc: ... here.
* nix/libutil/util.hh (struct Agent, commonChildInit): New
declarations.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2020-01-12 00:19:09 +0100'>2020-01-12</span></td><td><a href='/guix/commit/nix/libutil/util.hh?id=7033c7692ccbbbad8f7b9952015de071a5588e87'>daemon: Account for deleted store files when deduplication is on.</a><span class='msg-avail'>...<span class='msg-tooltip'>Previously, a store item that is a regular file would not be accounted
for in the 'bytesFreed' value computed by 'deletePath' because its
'st_nlink' count would always be &gt;= 2.  This commit fixes that.

* nix/libutil/util.hh (deletePath): Add optional 'linkThreshold' argument.
* nix/libutil/util.cc (_deletePath): Add 'linkThreshold' argument and
honor it.  Pass it down in recursive call.
(deletePath): Add 'linkThreshold' and honor it.
* nix/libstore/gc.cc (LocalStore::deleteGarbage): Pass 'linkThreshold'
argument to 'deletePath', with a value of 2 when PATH is a store item
and deduplication is on.
</span></span></td><td>Ludovic Courtès</td></tr>