Small batch of Bril/Rust fixes #183

Job	Run time
rust-ci (brilirs/Cargo.toml)	1m 22s
rust-ci (bril-rs/Cargo.toml)	37s
rust-ci (bril-rs/bril2json/Cargo.toml)	1m 4s
rust-ci (bril-rs/brild/Cargo.toml)	59s
rust-ci (brilift/Cargo.toml)	1m 1s
rust-ci (bril-rs/rs2bril/Cargo.toml)	41s
rust-ci (bril-rs/brillvm/Cargo.toml)	3m 22s
test (cd bril-rs && make test TURNTARGS=-v)	3m 23s
test (cd bril-rs && make features)	2m 35s
test (cd brilirs && make test TURNTARGS=-v)	2m 8s
test (cd brilirs && make benchmark TURNTARGS=-v)	1m 45s
test (cd brilift && cargo build --release && make rt.o && make test TURNTARGS=-v)	3m 30s
test (cd brilift && cargo build --release && make rt.o && make benchmark TURNTARGS=-v)	4m 29s
	26m 56s

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