Update univalue to 1.1.1
This improves getblocktemplate performance by ~28% on my machine.
Exerpt from https://github.com/jgarzik/univalue/pull/66 which is
the primary change associated with the perf improvement:
When the hand-written destructor is removed, the compiler will automatically create a proper one, with correct noexcept. This allows std::vector<UniValue> to be resized without having to copy all elements first, which makes JSON generation of a bitcoin block (as in the benchmark "BlockToJsonVerbose") 25% faster on my machine. Author: @martinus
This update also includes some nice cleanup and a new reserve()
function that may allow us to squeeze out some more performance
in a few places.