ash: [VAR] Do not poplocalvars prematurely on regular utilities

ash: [VAR] Do not poplocalvars prematurely on regular utilities

Upstream commit:

    Date: Thu, 27 May 2010 11:50:19 +0800
    [VAR] Do not poplocalvars prematurely on regular utilities

    The recent cmdenviron removal broke regular utilities by calling
    poplocalvars too early.  This patch fixes that by postponing the
    poplocalvars for regular utilities until they have completed.

    In order to ensure that local still works, it is now a special
    built-in.

    Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>