app-crypt/nss ebuild notes

This ebuild only installs util binaries from the NSS library such as certutil. Those binaries are installed on test images to facilitate Tast tests and to provide other utilities.

The Chrome OS nss ebuild carries the following modifications vs. upstream:

• nss-3.38-shlibsign-path-pollution.patch
• nss-3.44-prefer-writable-tokens-for-trust.patch
• nss-3.68.2-nss-ld-fixup.patch

This is in sync with dev-libs/nss to make sure builds are consistent.