Change WEBGRP and CGIGRP defaults.

The web build uses WEBGRP and CGIGRP to determine group ownership
during the build phase.  When left unset, the default group is 'www'.
The problem is that if $USER is not in group 'www', the build will
fail due to lack of permissions via chgrp(1).

This change sets default values for WEBGRP and CGIGRP to $USER, unless
explicitly set during build time to prevent chgrp(1)-invoked build
failure.

Note:  This change has no effect for users currently setting WEBGRP
and CGIGRP, either via command-line or within scripts.

Reviewed by:	-www@ (silence)

share/mk/web.site.mk

@@ -19,12 +19,23 @@ WEBDIR?=	${.CURDIR:T}
 CGIDIR?=	${.CURDIR:T}
 DESTDIR?=	${HOME}/public_html
 
+_ID?=		/usr/bin/id
+_UID!=		${_ID} -u
+
 WEBOWN?=	${USER}
+.if (${_UID} > 0)
+WEBGRP?=	${USER}
+.else
 WEBGRP?=	www
+.endif
 WEBMODE?=	664
 
 CGIOWN?=	${USER}
+.if (${_UID} > 0)
+CGIGRP?=	${USER}
+.else
 CGIGRP?=	www
+.endif
 CGIMODE?=	775
 
 BUNZIP2?=	/usr/bin/bunzip2