Add licences for breakpad and libwebp to the allowlist

Those licences are found in breakpad and libwebp README.chromium from
google3 so add them to the allowlist (since they are allowed just not
listed).

Fixed: 451723867, 451723789
Change-Id: Ib2f5a3f227a3f0dc8471c3569714bd435e33203e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/7036502
Auto-Submit: Sylvain Defresne <sdefresne@chromium.org>
Commit-Queue: Jordan Brown <rop@google.com>
Reviewed-by: Jordan Brown <rop@google.com>

metadata/fields/custom/license_allowlist.py

@@ -59,6 +59,7 @@ ALLOWED_SPDX_LICENSES = frozenset([
     # permissive.
     # go/keep-sorted start case=no
     "0BSD",
+    "FSFUL",
     "GPL-2.0-with-autoconf-exception",
     "GPL-2.0-with-classpath-exception",
     "GPL-3.0-with-autoconf-exception",
@@ -82,7 +83,10 @@ ALLOWED_SPDX_LICENSES = frozenset([
     "BSL-1.0",
     "CC-BY-3.0",
     "CC-BY-4.0",
+    "CMU-Mach",
     "dtoa",
+    "FSFAP",
+    "FSFULLR",
     "FTL",
     "HPND",
     "HPND-sell-variant",