Use official API for disabling shallow clones
Optional resources do not need to be conditional

Resources are downloaded on-demand, so declarations don't need to be
wrapped in a conditional.
libsigrokdecode: only append to PKG_CONFIG_PATH once

`lib` is the same inside or outside of a resource("...").stage block.
Avoid "build.head?" in the DSL
Fewer conditionals in the class body
maker 2.31.6: Add option --with-postgresql
maker 2.31.6: Optionally configure MAKER for MPI
maker 2.31.6: Add bioinformatics tag
maker 2.31.7
maker 2.31.8

Closes #1450.

Signed-off-by: Shaun Jackman <sjackman@gmail.com>
fasta 36.3.7

Closes #1417.

Signed-off-by: Shaun Jackman <sjackman@gmail.com>
fasta: add 36.3.7 bottle.
blast 2.2.30: Update SHA

Upstream changed the tarball to fix a minor bug, and then later reverted back
to the initial release.

Revert "blast 2.2.30: Change SHA, and upstream fixed #1396"

This reverts commit 5fee678660602e18d231a1fd7a2fc4da302ddb61.

See #1396
See #1407
Closes #1449
blast: update 2.2.30 bottle.