git-gui: reinstate support for Tcl 8.4

Tcl 8.5 introduced an extended vsatisfies syntax that is not
supported by Tcl 8.4.

Since only Tcl 8.4 is required this presents a problem.

The extended syntax was used starting with Git 2.0.0 in commit
b3f0c5c (git-gui: tolerate major version changes when comparing the
git version, 2014-05-17), so that a major version change would still
satisfy the condition.

However, what we really want is just a basic version compare, so use
vcompare instead to restore compatibility with Tcl 8.4.

Signed-off-by: Kyle J. McKay <mackyle@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Pat Thoyts <patthoyts@users.sourceforge.net>

Author: mackyle

git-gui.sh

@@ -1286,7 +1286,7 @@ load_config 0
 apply_config
 
 # v1.7.0 introduced --show-toplevel to return the canonical work-tree
-if {[package vsatisfies $_git_version 1.7.0-]} {
+if {[package vcompare $_git_version 1.7.0] >= 0} {
 	if { [is_Cygwin] } {
 		catch {set _gitworktree [exec cygpath --windows [git rev-parse --show-toplevel]]}
 	} else {
@@ -1542,7 +1542,7 @@ proc rescan_stage2 {fd after} {
 		close $fd
 	}
 
-	if {[package vsatisfies $::_git_version 1.6.3-]} {
+	if {[package vcompare $::_git_version 1.6.3] >= 0} {
 		set ls_others [list --exclude-standard]
 	} else {
 		set ls_others [list --exclude-per-directory=.gitignore]