dev-libs/libxslt: Add DEPEND on virtual/pkgconfig-1 or later.

This fixes the build for people upgrading their chroot from before
pkgconfig was upgraded.

Pull request: https://github.com/gentoo/gentoo/pull/16976

BUG=chromium:1039058
TEST=./update_chroot

Change-Id: Ia1b83e1c9330068a2a51cc7936103c9687c6d8c5
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/overlays/portage-stable/+/2335453
Tested-by: Allen Webb <allenwebb@google.com>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
1 file changed