Automated commit: libchrome r1309810 uprev

Merge with upstream commit 8c5d926c7ccff0d04ad89d3aa4cc396ba53fbd7d

Update long-term-2300-Fix-partition_alloc-buildflag-generation-logic
patch because of the patch conflict.

Update build.gn to build with correct flags. crrev.com/c/5589806

Add backward-compatibility-0600-Revert-type-change-in-MD5Digest.patch
because of the type cast error from type update crrev.com/c/5589055.

BUG=b:345313622
TEST=sudo emerge libchrome

Change-Id: Ib91e52b8f7f512a1cc92e7bf921a0d6975a0510a
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/libchrome/+/5593344
Commit-Queue: Cici Ruan <cuicuiruan@google.com>
Reviewed-by: Grace Cham <hscham@chromium.org>
Tested-by: Cici Ruan <cuicuiruan@google.com>