dev-lang/solidity: version bump to 0.4.18

dev-lang/solidity: version bump to 0.4.18

The previous patch needed to build valid releases is no longer needed
since upstream now provides valid release tarballs.

A new patch is added to remove the download and static compile of jsoncpp
during the build. The dependency has been fixed on 1.8.1 since the code
does not compile with a newer version. Upstream actually fixes to 1.7.7
but that version isn't in the tree and 1.8.1 works.

Closes: https://bugs.gentoo.org/629998
Closes: https://bugs.gentoo.org/627940
Package-Manager: Portage-2.3.8, Repoman-2.3.4