Fix build issue with recent Poppler:
  <https://github.com/politza/pdf-tools/issues/372>.

This combines upstream commits
6cd76dec9aece2a8daa90f17ab77fbf773157a1d..50a5297b82e26cfd52f6c00645ddc1057099d6a7
for this file.

diff --git a/server/poppler-hack.cc b/server/poppler-hack.cc
index 0c62f73..427f9df 100644
--- a/server/poppler-hack.cc
+++ b/server/poppler-hack.cc
@@ -51,7 +51,10 @@ GType poppler_annot_markup_get_type (void) G_GNUC_CONST;
     double y2;
   };
 
-  char *_xpoppler_goo_string_to_utf8(GooString *s)
+  // This function does not modify its argument s, but for
+  // compatibility reasons (e.g. getLength in GooString.h before 2015)
+  // with older poppler code, it can't be declared as such.
+  char *_xpoppler_goo_string_to_utf8(/* const */ GooString *s)
   {
     char *result;
 
@@ -85,7 +88,7 @@ GType poppler_annot_markup_get_type (void) G_GNUC_CONST;
   // Set the rectangle of an annotation.  It was first added in v0.26.
   void xpoppler_annot_set_rectangle (PopplerAnnot *a, PopplerRectangle *rectangle)
   {
-    GooString *state = a->annot->getAppearState ();
+    GooString *state = (GooString*) a->annot->getAppearState ();
     char *ustate = _xpoppler_goo_string_to_utf8 (state);
 
     a->annot->setRect (rectangle->x1, rectangle->y1,
@@ -105,7 +108,7 @@ GType poppler_annot_markup_get_type (void) G_GNUC_CONST;
     g_return_val_if_fail (POPPLER_IS_ANNOT_MARKUP (poppler_annot), NULL);
 
     annot = static_cast<AnnotMarkup *>(POPPLER_ANNOT (poppler_annot)->annot);
-    text = annot->getDate ();
+    text = (GooString*) annot->getDate ();
 
     return text ? _xpoppler_goo_string_to_utf8 (text) : NULL;
   }
ervices/version-control.scm'>
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<div class='path'>path: <a href='/guix/log/?id=5f55ca21051d37326afb3f8dd878340b5edd7015'>root</a>/<a href='/guix/log/gnu?id=5f55ca21051d37326afb3f8dd878340b5edd7015'>gnu</a>/<a href='/guix/log/gnu/services?id=5f55ca21051d37326afb3f8dd878340b5edd7015'>services</a>/<a href='/guix/log/gnu/services/version-control.scm?id=5f55ca21051d37326afb3f8dd878340b5edd7015'>version-control.scm</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/gnu/services/version-control.scm?id=5f55ca21051d37326afb3f8dd878340b5edd7015&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2018-03-20 17:17:58 +0100'>2018-03-20</span></td><td><a href='/guix/commit/gnu/services/version-control.scm?id=4a78fd4617908546be15d2c101f5cab512c71f8e'>Correct name and Email for ng0.</a><span class='msg-avail'>...</span></td><td>ng0</td></tr>
<tr><td><span title='2018-02-28 04:40:56 +0300'>2018-02-28</span></td><td><a href='/guix/commit/gnu/services/version-control.scm?id=e1cf4fd2d2fc0aab0f91c8ac961a8134cbefe200'>services: cgit: Add more configuration fields.</a><span class='msg-avail'>...</span></td><td>Oleg Pykhalov</td></tr>
<tr><td><span title='2018-01-21 00:24:03 +0100'>2018-01-21</span></td><td><a href='/guix/commit/gnu/services/version-control.scm?id=d466b1fc8221a6224fe7ded53a828f9c29ed9457'>services: Missing services are automatically instantiated.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2017-12-18 12:03:14 +0100'>2017-12-18</span></td><td><a href='/guix/commit/gnu/services/version-control.scm?id=8b223ceac4ff0781e95d69362875f87cff03f4d6'>services: nginx: Replace 'http-port' and 'https-port' with 'listen'.</a><span class='msg-avail'>...</span></td><td>Clément Lassieur</td></tr>
<tr><td><span title='2017-11-28 23:34:25 +0100'>2017-11-28</span></td><td><a href='/guix/commit/gnu/services/version-control.scm?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='2017-11-28 23:34:25 +0100'>2017-11-28</span></td><td><a href='/guix/commit/gnu/services/version-control.scm?id=410349347a7f38b7052d7574a629dd2660d018e0'>services: Add Git HTTP(S) service support.</a><span class='msg-avail'>...</span></td><td>Andy Wingo</td></tr>
<tr><td><span title='2017-10-03 17:07:54 +0200'>2017-10-03</span></td><td><a href='/guix/commit/gnu/services/version-control.scm?id=032a2760eef6dc64fa36f2fb3a211b755d5124bb'>gnu: services: Add cgit.</a><span class='msg-avail'>...</span></td><td>Oleg Pykhalov</td></tr>
<tr><td><span title='2016-11-21 20:37:43 +0800'>2016-11-21</span></td><td><a href='/guix/commit/gnu/services/version-control.scm?id=e01e2c6c525f1c0ef0ab62b832435a4ece0348ec'>gnu: services: Add git-service.</a><span class='msg-avail'>...</span></td><td>ng0</td></tr>