This patch makes the UUIDs in the XMP header optional, depending on the
setting of the environment variable GS_GENERATE_UUIDS.

If the environment variable GS_GENERATE_UUIDS is set to "0" or "no", it will
not write out the Document UUID field and also will write the Instance ID
field value as "".

Upstream does not want to do this.

See: https://bugs.ghostscript.com/show_bug.cgi?id=698208
diff -ur orig/gnu-ghostscript-9.14.0/devices/vector/gdevpdfe.c aa/gnu-ghostscript-9.14.0/devices/vector/gdevpdfe.c
--- orig/gnu-ghostscript-9.14.0/devices/vector/gdevpdfe.c	2017-07-09 23:30:28.960479189 +0200
+++ gnu-ghostscript-9.14.0/devices/vector/gdevpdfe.c	2017-07-10 01:04:12.252478276 +0200
@@ -620,7 +620,7 @@
         return code;
 
     /* PDF/A XMP reference recommends setting UUID to empty. If not empty must be a URI */
-    if (pdev->PDFA != 0)
+    if (pdev->PDFA != 0 || (getenv("GS_GENERATE_UUIDS") && (strcasecmp(getenv("GS_GENERATE_UUIDS"), "0") == 0 || strcasecmp(getenv("GS_GENERATE_UUIDS"), "no") == 0)))
         instance_uuid[0] = 0x00;
 
     cre_date_time_len = pdf_get_docinfo_item(pdev, "/CreationDate", cre_date_time, sizeof(cre_date_time));
@@ -720,14 +720,17 @@
             pdf_xml_tag_close(s, "rdf:Description");
             pdf_xml_newline(s);
 
-            pdf_xml_tag_open_beg(s, "rdf:Description");
-            pdf_xml_copy(s, " rdf:about=\"\"");
-            pdf_xml_attribute_name(s, "xmlns:xapMM");
-            pdf_xml_attribute_value(s, "http://ns.adobe.com/xap/1.0/mm/");
-            pdf_xml_attribute_name(s, "xapMM:DocumentID");
-            pdf_xml_attribute_value(s, document_uuid);
-            pdf_xml_tag_end_empty(s);
-            pdf_xml_newline(s);
+            if (!getenv("GS_GENERATE_UUIDS") || (strcasecmp(getenv("GS_GENERATE_UUIDS"), "0") != 0 && strcasecmp(getenv("GS_GENERATE_UUIDS"), "no") != 0))
+            {
+                pdf_xml_tag_open_beg(s, "rdf:Description");
+                pdf_xml_copy(s, " rdf:about=\"\"");
+                pdf_xml_attribute_name(s, "xmlns:xapMM");
+                pdf_xml_attribute_value(s, "http://ns.adobe.com/xap/1.0/mm/");
+                pdf_xml_attribute_name(s, "xapMM:DocumentID");
+                pdf_xml_attribute_value(s, document_uuid);
+                pdf_xml_tag_end_empty(s);
+                pdf_xml_newline(s);
+            }
 
             pdf_xml_tag_open_beg(s, "rdf:Description");
             pdf_xml_copy(s, " rdf:about=\"\"");
 class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/po/packages/POTFILES.in?id=ef500f9be43a375aa306a67c3b5263d228e6c0c0&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2017-11-28 23:34:25 +0100'>2017-11-28</span></td><td><a href='/guix/commit/po/packages/POTFILES.in?id=3af03e5967cf49ed1a4382dad7d75daa95ec5217'>services: certbot: Add default value and description.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2017-11-28 23:34:25 +0100'>2017-11-28</span></td><td><a href='/guix/commit/po/packages/POTFILES.in?id=a222b734b38f93b014b21e4d538002a5fec71b8a'>services: cgit, git-daemon: Add description and default value.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2017-09-16 17:47:46 +0200'>2017-09-16</span></td><td><a href='/guix/commit/po/packages/POTFILES.in?id=3f0de257c4071fcbb167fd47dbe6ffa71e95631a'>services: networking: Add descriptions.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2017-09-16 17:47:46 +0200'>2017-09-16</span></td><td><a href='/guix/commit/po/packages/POTFILES.in?id=6b9e1fefa40ecdd264fde9cb022b2b5359635ee5'>services: base: Add descriptions.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2017-07-15 19:25:39 +0800'>2017-07-15</span></td><td><a href='/guix/commit/po/packages/POTFILES.in?id=ee38fbcfaa5afc1cf2bb121a04bc9747b2339c37'>nls: Adjust to qemu.scm renaming.</a><span class='msg-avail'>...</span></td><td>宋文武</td></tr>
<tr><td><span title='2017-06-20 18:10:35 +0530'>2017-06-20</span></td><td><a href='/guix/commit/po/packages/POTFILES.in?id=148585c240f848ad08f6541ede7db3fca3411007'>gnu: Move contents of zip module into compression module.</a><span class='msg-avail'>...</span></td><td>Arun Isaac</td></tr>
<tr><td><span title='2016-12-05 20:54:58 +0100'>2016-12-05</span></td><td><a href='/guix/commit/po/packages/POTFILES.in?id=a79fbd5d1d59a0cbc998a8133177ddcc9b073b94'>nls: Adjust to geeqie.scm removal.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2016-12-04 22:32:40 +0100'>2016-12-04</span></td><td><a href='/guix/commit/po/packages/POTFILES.in?id=459978eae593dd5b51b567dbffe927eec4bbf2c3'>nls: Adjust to feh.scm renaming.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2016-08-04 19:38:33 +0200'>2016-08-04</span></td><td><a href='/guix/commit/po/packages/POTFILES.in?id=44210f84e274a3dd59da15d7bd2bd5f30f97efb4'>nls: Adjust to zsh.scm renaming.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2016-05-26 17:00:17 +0200'>2016-05-26</span></td><td><a href='/guix/commit/po/packages/POTFILES.in?id=f01c461994307c5e19ff14bc695cdf1d813880e0'>nls: Adjust to texlive.scm renaming.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>