Copied from Debian.

From: Jérémy Bobbio <lunar@debian.org>
Subject: Remove build date
Bug-Debian: http://bugs.debian.org/782851
 In order to make unzip build reproducibly, we remove the
 (already optional) build date from the binary.

--- a/unix/unix.c
+++ b/unix/unix.c
@@ -1705,7 +1705,7 @@
 #endif /* Sun */
 #endif /* SGI */
 
-#ifdef __DATE__
+#if 0
       " on ", __DATE__
 #else
       "", ""
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<tr><td><span title='2018-09-07 17:55:55 +0200'>2018-09-07</span></td><td><a href='/guix/commit/gnu/packages/gdb.scm?id=6b4f99102c4e3f57cc657c14ff196b211654f88b'>gnu: gdb: Update to 8.2.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2018-08-24 17:50:52 +0200'>2018-08-24</span></td><td><a href='/guix/commit/gnu/packages/gdb.scm?id=bf0bb925ea055496086fe0df48fc88977a5cc2cc'>gnu: gdb: Update to 8.1.1.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2018-04-12 04:03:06 -0400'>2018-04-12</span></td><td><a href='/guix/commit/gnu/packages/gdb.scm?id=a3401d64dbedf72c346e36624403102933e13c88'>gnu: gdb: Return #t from all phases.</a><span class='msg-avail'>...</span></td><td>Mark H Weaver</td></tr>
<tr><td><span title='2018-01-31 23:31:38 +0100'>2018-01-31</span></td><td><a href='/guix/commit/gnu/packages/gdb.scm?id=31bd4175c9c999f5ef4f59ee4c707d27883d0cb3'>gnu: gdb: Update to 8.1.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2017-09-11 11:57:51 +0200'>2017-09-11</span></td><td><a href='/guix/commit/gnu/packages/gdb.scm?id=130c3bc8948cb249129b3310561d9a2553926a60'>gnu: gdb: Update to 8.0.1.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>