git-gui: Refactor the add to commit state filters.

The list of states which are valid for update-index were a little
too verbose and fed a few too many cases to the program.  We can
do better with less lines of code by using more pattern matching,
and since we already were globbing here there's little change in
runtime cost.
Signed-off-by: NShawn O. Pearce <spearce@spearce.org>

git-gui.sh

@@ -1512,26 +1512,15 @@ proc write_update_index {fd pathList totalCnt batch msg after} {
 		incr update_index_cp
 
 		switch -glob -- [lindex $file_states($path) 0] {
-		AD -
-		MD -
-		UD -
-		_D {set new D_}
-
-		_M -
-		MM -
-		UM -
-		U_ -
-		M_ {set new M_}
-
+		AD {set new __}
+		?D {set new D_}
 		_O -
-		AM -
-		A_ {set new A_}
-
+		AM {set new A_}
+		U_ -
+		?M {set new M_}
 		?? {continue}
 		}
-
-		puts -nonewline $fd $path
-		puts -nonewline $fd "\0"
+		puts -nonewline $fd "$path\0"
 		display_file $path $new
 	}
 
@@ -2333,14 +2322,10 @@ proc add_helper {txt paths} {
 	set after {}
 	foreach path $paths {
 		switch -glob -- [lindex $file_states($path) 0] {
-		AM -
-		AD -
-		MM -
-		MD -
-		U? -
-		_M -
-		_D -
-		_O {
+		_O -
+		?M -
+		?D -
+		U? {
 			lappend pathList $path
 			if {$path eq $current_diff} {
 				set after {reshow_diff;}
@@ -2377,18 +2362,13 @@ proc do_add_all {} {
 
 	set paths [list]
 	foreach path [array names file_states] {
-		switch -- [lindex $file_states($path) 0] {
-		AM -
-		AD -
-		MM -
-		MD -
-		_M -
-		_D {lappend paths $path}
+		switch -glob -- [lindex $file_states($path) 0] {
+		U? {continue}
+		?M -
+		?D {lappend paths $path}
 		}
 	}
-	add_helper \
-		{Adding all modified files} \
-		$paths
+	add_helper {Adding all changed files} $paths
 }
 
 proc revert_helper {txt paths} {