setup: compute gitrev from outside of chroot

Together with previous commit, `xbps-src` is able to support
git-worktree and shared repository by now.

common/xbps-src/shutils/chroot.sh

@@ -175,6 +175,7 @@ chroot_handler() {
             ${HTTP_PROXY_AUTH:+HTTP_PROXY_AUTH="${HTTP_PROXY_AUTH}"} \
             ${FTP_RETRIES:+FTP_RETRIES="${FTP_RETRIES}"} \
             SOURCE_DATE_EPOCH="$SOURCE_DATE_EPOCH" \
+            XBPS_GIT_REVS="$XBPS_GIT_REVS" \
             XBPS_ALLOW_CHROOT_BREAKOUT="$XBPS_ALLOW_CHROOT_BREAKOUT" \
             $XBPS_COMMONDIR/chroot-style/${XBPS_CHROOT_CMD:=uunshare}.sh \
             $XBPS_MASTERDIR $XBPS_DISTDIR "$XBPS_HOSTDIR" "$XBPS_CHROOT_CMD_ARGS" \