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
@@ -617,7 +617,7 @@
         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));
@@ -719,15 +719,18 @@
             pdf_xml_tag_close(s, "rdf:Description");
             pdf_xml_newline(s);
 
-            pdf_xml_tag_open_beg(s, "rdf:Description");
-            pdf_xml_attribute_name(s, "rdf:about");
-            pdf_xml_attribute_value(s, instance_uuid);
-            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_attribute_name(s, "rdf:about");
+                pdf_xml_attribute_value(s, instance_uuid);
+                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_attribute_name(s, "rdf:about");
showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2020-10-08 20:21:02 +0100'>2020-10-08</span></td><td><a href='/guix/commit/gnu/services/guix.scm?id=65c9f07a1616382c00d23b83d7a42b0e72dd8df8'>services: guix: Don't use normalized codeset for Guix Data Service.</a><span class='msg-avail'>...</span></td><td>Christopher Baines</td></tr>
<tr><td><span title='2020-10-05 18:10:48 +0100'>2020-10-05</span></td><td><a href='/guix/commit/gnu/services/guix.scm?id=c14714cbbfe9239410aec2ed73282192a64fbbdc'>services: guix: Add guix-build-coordinator-queue-builds-service-type.</a><span class='msg-avail'>...</span></td><td>Christopher Baines</td></tr>
<tr><td><span title='2020-10-05 18:10:48 +0100'>2020-10-05</span></td><td><a href='/guix/commit/gnu/services/guix.scm?id=98ab323a246df47610652eca81494c777b50c251'>services: guix: Add guix-build-coordinator-agent-service-type.</a><span class='msg-avail'>...</span></td><td>Christopher Baines</td></tr>
<tr><td><span title='2020-10-05 18:10:48 +0100'>2020-10-05</span></td><td><a href='/guix/commit/gnu/services/guix.scm?id=15955e9b54b8d9c1275d68a0f2b6ccbc5f6c3878'>services: guix: Add guix-build-coordinator-service-type.</a><span class='msg-avail'>...</span></td><td>Christopher Baines</td></tr>
<tr><td><span title='2020-03-08 23:35:03 +0000'>2020-03-08</span></td><td><a href='/guix/commit/gnu/services/guix.scm?id=d8ab68b92941ca0286697b87a88254023a0b2dc9'>services: guix-data-service: Allow passing extra options.</a><span class='msg-avail'>...</span></td><td>Christopher Baines</td></tr>
<tr><td><span title='2019-09-25 08:35:33 +0100'>2019-09-25</span></td><td><a href='/guix/commit/gnu/services/guix.scm?id=dd2a83270bccb539439b2fc831d0db04e5276f11'>services: Add the Guix Data Service.</a><span class='msg-avail'>...</span></td><td>Christopher Baines</td></tr>