Minor linux-specific changes

[gasbytes]

• Updated the docs for the linux based builds and removed the build.sh file, fixes some bindings generation related errors that @JacobBarthelmeh ran into while testing on Ubuntu (Thank you Jacob!);
• Minor bug fix in the sec384r1 trait implementation;
• Removed sudo from the build.rs file;

[JacobBarthelmeh]

These new README steps fail for me. Please clarify them if I'm missing something here, it looks like a make build from the root directory should be able to happen? This is what I do:

cd rustls-wolfcrypt-provider
bash-3.2$ make build
make: *** No rule to make target `build'.  Stop.

Then tried:

cd rustls-wolfcrypt-provider
cd wolfcrypt-rs
bash-3.2$ make build
warning: `extern` block uses type `u128`, which is not FFI-safe
    --> /Users/jacob/Documents/rustls-wolfcrypt-provider/wolfcrypt-rs/target/release/build/wolfcrypt-rs-74468657843a1c19/out/bindings.rs:8981:10
     |
8981 |     ) -> u128;
     |          ^^^^ not FFI-safe
     |
     = note: 128-bit integers don't currently have a known stable ABI
     = note: `#[warn(improper_ctypes)]` on by default

warning: `wolfcrypt-rs` (lib) generated 1 warning
    Finished `release` profile [optimized] target(s) in 0.13s
make bash-3.2$ make test
warning: `extern` block uses type `u128`, which is not FFI-safe
    --> /Users/jacob/Documents/rustls-wolfcrypt-provider/wolfcrypt-rs/target/debug/build/wolfcrypt-rs-f8b81ac45dfc0c9d/out/bindings.rs:8981:10
     |
8981 |     ) -> u128;
     |          ^^^^ not FFI-safe
     |
     = note: 128-bit integers don't currently have a known stable ABI
     = note: `#[warn(improper_ctypes)]` on by default

warning: `wolfcrypt-rs` (lib) generated 1 warning
warning: `wolfcrypt-rs` (lib test) generated 1 warning (1 duplicate)
    Finished `test` profile [unoptimized + debuginfo] target(s) in 0.07s
     Running unittests src/lib.rs (target/debug/deps/wolfcrypt_rs-ed2075781d0d8f25)

running 1 test
test tests::rsa_encrypt_decrypt ... ok

test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.56s

   Doc-tests wolfcrypt_rs

running 0 tests

test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s

bash-3.2$ cd ../
bash-3.2$ make build
make: *** No rule to make target `build'.  Stop.