libgcrypt: Respect portage host cc variable

Pass CC_FOR_BUILD to econf. Otherwise it invokes gcc instead of portage
specified HOST/BUILD CC.

Gentoo PR: https://github.com/gentoo/gentoo/pull/16151

BUG=chromium:979916, chromium:991812
TEST=CQ

Change-Id: Icf21aab2c3dccd6f17be14e3803d953fd6bacaaf
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/overlays/portage-stable/+/2240123
Tested-by: Manoj Gupta <manojgupta@chromium.org>
Reviewed-by: George Burgess <gbiv@chromium.org>
1 file changed