blast: Support recent versions of gnutls
blast: Support recent versions of gnutls

Add an upstream patch to support recent versions of gnutls.
Add an optional build dependency on gnutls.
Add configure --without-debug --with-mt as recommended by upstream.
Closes #161, closes #170.

goxberry/homebrew-science,dpo/homebrew-science,philippbayer/homebrew-science,kozo2/homebrew-science,DabeDotCom/homebrew-science,ahundt/homebrew-science,ge11232002/homebrew-science,joshbode/homebrew-science,parcollet/homebrew-science,pditommaso/homebrew-science,andrewjpage/homebrew-science,aeantipov/homebrew-science,quantumsteve/homebrew-science,pmelsted/homebrew-science,heuermh/homebrew-science,maplesond/homebrew-science