gitk: Tcl9 doesn't expand ~, use $env(HOME)

gitk looks for configuration files under $(HOME)/.., and uses the
typical shortcut formats to find this, e.g., ~/.config/. This relies
upon Tcl expanding such constructs to replace ~ with $(HOME). But, Tcl 9
has stopped doing that for various reasons, and now supplies [file
tildeexpand ...] to perform this expansion.

There are a very few places that need this expansion, and all must be
modified regardless of appraoch taken.

POSIX specifies that $HOME be defined at the time of login, and both
Cygwin and MSYS (underlying git for windows) set this variable. Tcl8
uses pwnam to look up the underlying database record on Unix, but will
get the same result as using $HOME on any POSIX compliant system. On
Windows, Tcl just accesses $HOME, falling back to other environment
variables if $HOME is not set.  Git for Windows has $HOME defined by
MSYS, so this works just as on the others.

As $env(HOME) works in Tcl 8 and 9, while anything using [file
tildeexpand ... ] will not, let's use the simpler approah as doing so
adds no lines of code.

Signed-off-by: Mark Levedahl <[email protected]>

Author: mark987

gitk

@@ -12625,14 +12625,14 @@ catch {
         set config_file_tmp [file join $env(XDG_CONFIG_HOME) git gitk-tmp]
     } else {
         # default XDG_CONFIG_HOME
-        set config_file "~/.config/git/gitk"
-        set config_file_tmp "~/.config/git/gitk-tmp"
+        set config_file "$env(HOME)/.config/git/gitk"
+        set config_file_tmp "$env(HOME)/.config/git/gitk-tmp"
     }
     if {![file exists $config_file]} {
         # for backward compatibility use the old config file if it exists
-        if {[file exists "~/.gitk"]} {
-            set config_file "~/.gitk"
-            set config_file_tmp "~/.gitk-tmp"
+        if {[file exists "$env(HOME)/.gitk"]} {
+            set config_file "$env(HOME)/.gitk"
+            set config_file_tmp "$env(HOME)/.gitk-tmp"
         } elseif {![file exists [file dirname $config_file]]} {
             file mkdir [file dirname $config_file]
         }