Improve how build deps are processed, return on errors immediately.

xbps-src/libexec/xbps-src-doinst-helper.sh.in

@@ -64,7 +64,7 @@ install_src_phase()
 {
 	local f i subpkg lver spkgrev saved_wrksrc
 
-	[ -z $pkgname ] && return 1
+	[ -z $pkgname ] && return 2
 
 	if [ -n "$revision" ]; then
 		lver="${version}_${revision}"
@@ -205,9 +205,9 @@ make_install()
 		|| msg_error "$pkgname: make install failed!"
 }
 
-[ -z "$PKG_TMPLNAME" ] && exit 1
+[ -z "$PKG_TMPLNAME" ] && exit 2
 
 setup_tmpl $PKG_TMPLNAME
 install_src_phase $pkgname
 
-exit $?
+exit 0