Handle case where SHELL isn't set in Cygwin
mysql_client_test.dsp:
  Put output into the "client_debug" and "client_release" directories


VC++Files/tests/mysql_client_test.dsp:
  Put output into the "client_debug" and "client_release" directories
mysql-test/mysql-test-run.pl:
  Handle case where SHELL isn't set in Cygwin