Add Windows 2003 support to getProcEnvCommand() + minor refactoring.

PR:  28067
Submitted by:	Irene Rusman


git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@276268 13f79535-47bb-0310-9956-ffa450edef68

CONTRIBUTORS

@@ -65,6 +65,7 @@ Hiroaki Nakamura
 Holger Engels
 Ingenonsya France
 Ingmar Stein
+Irene Rusman
 James Duncan Davidson
 Jan Matèrne
 Jason Hunter