Support & build test no_std/alloc

[pinkforest]

There are some dependencies that need to be checked for no_std to be supported

cargo build --target thumbv7em-none-eabi --release --no-default-features --features alloc

EDIT: It seems getrandom creeps from somewhere 👀 tracing up in #28

Too tired but one of them is bringing it...

$ cargo tree -i getrandom --no-default-features
getrandom v0.2.12
└── rand_core v0.6.4
    ├── crypto-bigint v0.5.5
    │   └── elliptic-curve v0.13.8
    │       ├── ecdsa v0.16.9
    │       │   ├── p256 v0.13.2
    │       │   │   └── rustls-rustcrypto v0.1.0 (/home/foobar/code/rustls-rustcrypto/rustls-provider-rustcrypto)
    │       │   │       └── self-validate v0.1.0 (/home/foobar/code/rustls-rustcrypto/self-validate)
    │       │   ├── p384 v0.13.0
    │       │   │   └── rustls-rustcrypto v0.1.0 (/home/foobar/code/rustls-rustcrypto/rustls-provider-rustcrypto) (*)
    │       │   └── rustls-rustcrypto v0.1.0 (/home/foobar/code/rustls-rustcrypto/rustls-provider-rustcrypto) (*)
    │       ├── p256 v0.13.2 (*)
    │       ├── p384 v0.13.0 (*)
    │       └── primeorder v0.13.6
    │           ├── p256 v0.13.2 (*)
    │           └── p384 v0.13.0 (*)
    ├── elliptic-curve v0.13.8 (*)
    ├── ff v0.13.0
    │   ├── elliptic-curve v0.13.8 (*)
    │   └── group v0.13.0
    │       └── elliptic-curve v0.13.8 (*)
    ├── group v0.13.0 (*)
    ├── rand v0.8.5
    │   └── num-bigint-dig v0.8.4
    │       └── rsa v0.9.6
    │           └── rustls-rustcrypto v0.1.0 (/home/foobar/code/rustls-rustcrypto/rustls-provider-rustcrypto) (*)
    ├── rand_chacha v0.3.1
    │   └── rand v0.8.5 (*)
    ├── rsa v0.9.6 (*)
    ├── rustls-rustcrypto v0.1.0 (/home/foobar/code/rustls-rustcrypto/rustls-provider-rustcrypto) (*)
    ├── signature v2.2.0
    │   ├── ecdsa v0.16.9 (*)
    │   ├── ed25519 v2.2.3
    │   │   └── ed25519-dalek v2.1.1
    │   │       └── rustls-rustcrypto v0.1.0 (/home/foobar/code/rustls-rustcrypto/rustls-provider-rustcrypto) (*)
    │   ├── rsa v0.9.6 (*)
    │   └── rustls-rustcrypto v0.1.0 (/home/foobar/code/rustls-rustcrypto/rustls-provider-rustcrypto) (*)
    └── x25519-dalek v2.0.1
        └── rustls-rustcrypto v0.1.0 (/home/foobar/code/rustls-rustcrypto/rustls-provider-rustcrypto) (*)

[newpavlov]

You need to disable default features for ed25519-dalek.

[pinkforest]

Awesome thanks - how did I miss that 😪 now need to chase and fix

• API for providing Rng #41

[pinkforest]

PR up for minimizing + feature mapping of dependencies

• Use dependencies default-features = false where possible #43

[pinkforest]

Looks like this was done in:

• CI: test build on actual no_std platforms #67