git-gui: if a background colour is set, set foreground colour as well

In several places, only the background colour is set to an explicit
value, sometimes even "white".  This does not work well with dark
colour themes.

This patch tries to set the foreground colour to "black" in those
situations, where an explicit background colour is set without defining
any foreground colour.

Signed-off-by: Philipp A. Hartmann <ph@sorgh.de>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
diff --git a/lib/console.tcl b/lib/console.tcl
index 5597188..c112464 100644
--- a/lib/console.tcl
+++ b/lib/console.tcl
@@ -46,7 +46,9 @@
 		-justify left \
 		-font font_uibold
 	text $w_t \
-		-background white -borderwidth 1 \
+		-background white \
+		-foreground black \
+		-borderwidth 1 \
 		-relief sunken \
 		-width 80 -height 10 \
 		-wrap none \
@@ -180,7 +182,8 @@
 	if {$ok} {
 		if {[winfo exists $w.m.s]} {
 			bind $w.m.s <Destroy> [list delete_this $this]
-			$w.m.s conf -background green -text [mc "Success"]
+			$w.m.s conf -background green -foreground black \
+				-text [mc "Success"]
 			if {$is_toplevel} {
 				$w.ok conf -state normal
 				focus $w.ok
@@ -193,7 +196,8 @@
 			_init $this
 		}
 		bind $w.m.s <Destroy> [list delete_this $this]
-		$w.m.s conf -background red -text [mc "Error: Command Failed"]
+		$w.m.s conf -background red -foreground black \
+			-text [mc "Error: Command Failed"]
 		if {$is_toplevel} {
 			$w.ok conf -state normal
 			focus $w.ok