dbus/wscript: remove Windows conditional

git commit 8d7faa5bea
made installation of jack_control depend on bulid host operating
system.

While the commit correcty moved jack_control out of tools,
in https//ladish.org/jackdbus.html context jack_control is always to
be installed, as D-Bus is enabled by definition.

In context of jackaudio.org/jack2 project distributing jack_control
optionally, it makes sense to correct the conditional to depend on
dbus configure time flag.

dbus/wscript

@@ -112,5 +112,4 @@ def build(bld):
             install_path='${DBUS_SERVICES_DIR}/',
             BINDIR=bld.env['PREFIX'] + '/bin')
 
-    if not bld.env['IS_WINDOWS']:
-        bld.install_files('${PREFIX}/bin', 'jack_control', chmod=0o755)
+    bld.install_files('${PREFIX}/bin', 'jack_control', chmod=0o755)