portage: Bubble up all any-of failures

We lose valuable information if we just pick the first error.
Let's bubble it up:

> WARNING: Failed to analyze dependencies: Resolving build-time host dependencies for dev-libs/libjcat-0.2.0: Unsatisfiable dependency: any-of ( No package satisfies >=dev-lang/python-3.8.15_p3:3.8[xml], No package satisfies >=dev-lang/python-3.9.15_p3:3.9[xml], No package satisfies >=dev-lang/python-3.10.8_p3:3.10[xml], Error matching >=dev-lang/python-3.11.0_p2:3.11[xml]: Target is missing 'xml' USE flag and no default specified )

BUG=none
TEST=bazel run //:alchemist -- dump-package --board amd64-generic dev-libs/libjcat

Change-Id: I0abe1e0b6a8a2de10b391e5e29e5b82931b4371c
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/bazel/+/6182505
Commit-Queue: Shuhei Takahashi <nya@chromium.org>
Auto-Submit: Raul Rangel <rrangel@chromium.org>
Tested-by: Raul Rangel <rrangel@chromium.org>
Reviewed-by: Shuhei Takahashi <nya@chromium.org>