Fixes undefined reference to `Fl_XFont_On_Demand::value()'.
From <http://www.fltk.org/str.php?L3156+P0+S0+C0+I0+E0+V1+QOn_Demand>.

Index: src/fl_font.cxx
===================================================================
--- fltk-1.3.3/src/fl_font.cxx	(revision 10503)
+++ fltk-1.3.3/src/fl_font.cxx	(revision 10504)
@@ -55,6 +55,12 @@
 #  include "fl_font_x.cxx"
 #endif // WIN32
 
+#if ! (defined(WIN32) || defined(__APPLE__))
+XFontStruct *fl_X_core_font()
+{
+  return fl_xfont.value();
+}
+#endif
 
 double fl_width(const char* c) {
   if (c) return fl_width(c, (int) strlen(c));
Index: src/gl_draw.cxx
===================================================================
--- fltk-1.3.3/src/gl_draw.cxx	(revision 10503)
+++ fltk-1.3.3/src/gl_draw.cxx	(revision 10504)
@@ -81,7 +81,7 @@
  * then sorting through them at draw time (for normal X rendering) to find which one can
  * render the current glyph... But for now, just use the first font in the list for GL...
  */
-    XFontStruct *font = fl_xfont;
+    XFontStruct *font = fl_X_core_font();
     int base = font->min_char_or_byte2;
     int count = font->max_char_or_byte2-base+1;
     fl_fontsize->listbase = glGenLists(256);
Index: FL/x.H
===================================================================
--- fltk-1.3.3/FL/x.H	(revision 10503)
+++ fltk-1.3.3/FL/x.H	(revision 10504)
@@ -132,6 +132,7 @@
   XFontStruct *ptr;
 };
 extern FL_EXPORT Fl_XFont_On_Demand fl_xfont;
+extern FL_EXPORT XFontStruct* fl_X_core_font();
 
 // this object contains all X-specific stuff about a window:
 // Warning: this object is highly subject to change!  
ages/kde-pim.scm'>
<input type='hidden' name='id' value='072cc8d1415a2abf66b36249c61658a828dead88'/><select name='qt'>
<option value='grep'>log msg</option>
<option value='author'>author</option>
<option value='committer'>committer</option>
<option value='range'>range</option>
</select>
<input class='txt' type='search' size='10' name='q' value=''/>
<input type='submit' value='search'/>
</form>
</td></tr></table>
<div class='path'>path: <a href='/guix/log/?id=072cc8d1415a2abf66b36249c61658a828dead88'>root</a>/<a href='/guix/log/gnu?id=072cc8d1415a2abf66b36249c61658a828dead88'>gnu</a>/<a href='/guix/log/gnu/packages?id=072cc8d1415a2abf66b36249c61658a828dead88'>packages</a>/<a href='/guix/log/gnu/packages/kde-pim.scm?id=072cc8d1415a2abf66b36249c61658a828dead88'>kde-pim.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/packages/kde-pim.scm?id=072cc8d1415a2abf66b36249c61658a828dead88&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2022-09-01 16:08:17 +0200'>2022-09-01</span></td><td><a href='/guix/commit/gnu/packages/kde-pim.scm?id=752ae1f24463d01e3fac932dddde701793aa3855'>gnu: kmessagelib: Remove qtwebkit as an input.</a><span class='msg-avail'>...</span></td><td>Brendan Tildesley</td></tr>
<tr><td><span title='2022-09-01 16:08:16 +0200'>2022-09-01</span></td><td><a href='/guix/commit/gnu/packages/kde-pim.scm?id=c60a78b1b7a1aa6f5a72907f4a7392be5fe6922d'>gnu: KDE PIM: Update home-pages.</a><span class='msg-avail'>...</span></td><td>Petr Hodina</td></tr>
<tr><td><span title='2022-09-01 16:08:15 +0200'>2022-09-01</span></td><td><a href='/guix/commit/gnu/packages/kde-pim.scm?id=d04997fadfd33b90224bd5c9770db44e41f0463b'>gnu: libgravatar: Remove input labels.</a><span class='msg-avail'>...</span></td><td>Petr Hodina</td></tr>
<tr><td><span title='2022-09-01 16:08:15 +0200'>2022-09-01</span></td><td><a href='/guix/commit/gnu/packages/kde-pim.scm?id=0d3d6fd71b94268ca7a5add1f39205be73586e15'>gnu: libgravatar: Move to (gnu packages kde-pim).</a><span class='msg-avail'>...</span></td><td>Brendan Tildesley</td></tr>
<tr><td><span title='2022-09-01 16:08:15 +0200'>2022-09-01</span></td><td><a href='/guix/commit/gnu/packages/kde-pim.scm?id=53d645c1b1d1e44513c9c0d30678371124906e97'>gnu: kdav: Move to (gnu packages kde-frameworks).</a><span class='msg-avail'>...</span></td><td>Brendan Tildesley</td></tr>
<tr><td><span title='2022-07-31 21:55:48 -0400'>2022-07-31</span></td><td><a href='/guix/commit/gnu/packages/kde-pim.scm?id=2e27ccec8307961feabbb85589ace67431672c70'>gnu: qtnetworkauth: Rename to qtnetworkauth-5.</a><span class='msg-avail'>...</span></td><td>Maxim Cournoyer</td></tr>
<tr><td><span title='2022-07-31 21:55:48 -0400'>2022-07-31</span></td><td><a href='/guix/commit/gnu/packages/kde-pim.scm?id=eef8e2ec46c4155980815e00a394428c0c3de075'>gnu: qttools: Rename to qttools-5.</a><span class='msg-avail'>...</span></td><td>Maxim Cournoyer</td></tr>
<tr><td><span title='2022-07-31 21:55:47 -0400'>2022-07-31</span></td><td><a href='/guix/commit/gnu/packages/kde-pim.scm?id=a0beb297a352930b89051ff258a06d78f224d6b9'>gnu: qtwebengine: Rename to qtwebengine-5.</a><span class='msg-avail'>...</span></td><td>Maxim Cournoyer</td></tr>
<tr><td><span title='2022-07-31 21:55:46 -0400'>2022-07-31</span></td><td><a href='/guix/commit/gnu/packages/kde-pim.scm?id=0938c3e34a9004948baa56bb21017d20fb9c9c26'>gnu: qtwebchannel: Rename to qtwebchannel-5.</a><span class='msg-avail'>...</span></td><td>Maxim Cournoyer</td></tr>
<tr><td><span title='2022-07-31 21:55:44 -0400'>2022-07-31</span></td><td><a href='/guix/commit/gnu/packages/kde-pim.scm?id=735d340ae461751eaebf177334dec537da7cfec2'>gnu: qtdeclarative: Rename to qtdeclarative-5.</a><span class='msg-avail'>...</span></td><td>Maxim Cournoyer</td></tr>
<tr><td><span title='2022-04-19 20:05:01 +0300'>2022-04-19</span></td><td><a href='/guix/commit/gnu/packages/kde-pim.scm?id=cd23250c16ea233c7dc29ec1f8a5cea7c1fe159e'>gnu: kmessagelib: Fix building.</a><span class='msg-avail'>...</span></td><td>Efraim Flashner</td></tr>
<tr><td><span title='2022-03-29 14:43:21 +0300'>2022-03-29</span></td><td><a href='/guix/commit/gnu/packages/kde-pim.scm?id=3b0c9e4c20de181bac5cb8076e052bf00932f533'>gnu: kpeoplevcard: Use mirror URI.</a><span class='msg-avail'>...</span></td><td>Efraim Flashner</td></tr>