pkg/47296: Add autoswc support to pkg_comp

[jmmv%netbsd.org@localhost]

>Number:         47296
>Category:       pkg
>Synopsis:       Add autoswc support to pkg_comp
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    pkg-manager
>State:          open
>Class:          change-request
>Submitter-Id:   net
>Arrival-Date:   Fri Dec 07 16:40:00 +0000 2012
>Originator:     Julio Merino
>Release:        NetBSD 5.1_STABLE
>Organization:
Julio Merino
>Environment:
        
        
System: NetBSD homeworld.netbsd.org 5.1_STABLE NetBSD 5.1_STABLE (NBMAIL) #2: 
Mon Jun 11 07:45:45 UTC 2012 
root%franklin.NetBSD.org@localhost:/home/netbsd/5/amd64/kern-compile/NBMAIL 
amd64
Architecture: x86_64
Machine: amd64
>Description:
        It would be nice if pkg_comp had a simple mechanism to enable builds
        with pkgtools/autoswc.  This requires a configuration setting and a
        hook to run the autoswc configuration on startup automatically.
        
        Maybe there should even be some support to specify an autoswc
        configuration file that lives outside of the chroot so that the things
        to cache would be configured once and persist across rebuilds of the
        chroot.  But this is not high priority: we can use the default
        configuration file as a first iteration, which should "just work".

        The goal of this change is to make builds of multiple packages faster
        by avoiding repeated runs of very similar configure scripts.  This is
        interesting for slow platforms.
>How-To-Repeat:
        
>Fix:
        

>Unformatted: