gitk: Set the font for all spinbox widgets

Use the X resources to set the font, removing the need to set the font
for specific widgets.

Signed-off-by: Mark Hills <mark@pogo.org.uk>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/gitk b/gitk
index 59970af..f1e70ad 100755
--- a/gitk
+++ b/gitk
@@ -1879,6 +1879,7 @@
     option add *Message.font uifont startupFile
     option add *Entry.font uifont startupFile
     option add *Labelframe.font uifont startupFile
+    option add *Spinbox.font textfont startupFile
 }
 
 # Make a menu and submenus.
@@ -2229,7 +2230,7 @@
 	-command changediffdisp -variable diffelide -value {1 0}
     ${NS}::label .bleft.mid.labeldiffcontext -text "      [mc "Lines of context"]: "
     pack .bleft.mid.diff .bleft.mid.old .bleft.mid.new -side left
-    spinbox .bleft.mid.diffcontext -width 5 -font textfont \
+    spinbox .bleft.mid.diffcontext -width 5 \
 	-from 0 -increment 1 -to 10000000 \
 	-validate all -validatecommand "diffcontextvalidate %P" \
 	-textvariable diffcontextstring