Cleanup .gitignore
Cleanup .gitignore

Some things to ignore need to be properly rooted, and use a bit more
precision on ignoring 'lib', as that maybe be a perfectly valid
directory name to add into git elsewhere in the source tree.

Reviewed-by: Rich Salz <c04971a99e5a9ee80eaab4b1deb37e845b0bd697@openssl.org>

openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl