[linux] reprogram font before mapping framebuffer

You can't reprogram the Linux console font while holding
a map of the framebuffer, annoyingly. Move the attempt to
reprogram the fonts prior to the acquisition of the
framebuffer. The problem with this is that it clears the
framebuffer, so we're going to need to get a copy of it
beforehand, which we will reblit afterwards #2108.

src/lib/linux.c

@@ -637,7 +637,7 @@ int reprogram_console_font(tinfo* ti, unsigned no_font_changes,
     free(cfo.data);
     return -1;
   }
-  int r = reprogram_linux_font(ti->linux_fb_fd, &cfo, &map, no_font_changes,
+  int r = reprogram_linux_font(ti->ttyfd, &cfo, &map, no_font_changes,
                                halfblocks, quadrants);
   free(cfo.data);
   free(map.entries);

src/lib/termdesc.c

@@ -582,6 +582,11 @@ apply_term_heuristics(tinfo* ti, const char* termname, queried_terminals_e qterm
     if(uname(&un) == 0){
       ti->termversion = strdup(un.release);
     }
+    ti->caps.halfblocks = false;
+    ti->caps.braille = false; // no caps.braille, no caps.sextants in linux console
+    if(ti->ttyfd >= 0){
+      reprogram_console_font(ti, nonewfonts, &ti->caps.halfblocks, &ti->caps.quadrants);
+    }
     if(is_linux_framebuffer(ti)){
       termname = "Linux framebuffer";
       setup_fbcon_bitmaps(ti, ti->linux_fb_fd);
@@ -589,9 +594,6 @@ apply_term_heuristics(tinfo* ti, const char* termname, queried_terminals_e qterm
       termname = "Linux console";
     }
     // assume no useful unicode drawing unless we're positively sure
-    ti->caps.halfblocks = false;
-    reprogram_console_font(ti, nonewfonts, &ti->caps.halfblocks, &ti->caps.quadrants);
-    ti->caps.braille = false; // no caps.braille, no caps.sextants in linux console
 #else
 (void)nonewfonts;
 #endif