fix: resolved feature flags for openssl vendoring (#3287)

Description
---
Include vendored openssl library when not building ffi wallet library.
Exclude vendored openssl library when building ffi wallet library as it needs to be cross compiled for mobile which is done in mobile_build.sh.

Merge #3285 first.

We had to do the same for sqlite here:
#3073

Motivation and Context
---
Current:
![Screen Shot 2021-09-06 at 6 30 17 PM](https://user-images.githubusercontent.com/51991544/132251475-cce3d7e4-7237-4c70-8f40-c92b12d0091a.png)

This PR:
![Screen Shot 2021-09-06 at 8 06 48 PM](https://user-images.githubusercontent.com/51991544/132251455-bbdfbc5c-864f-416a-953f-9f8f6504666b.png)


[mobile_build_logs.zip](https://github.com/tari-project/tari/files/7104686/mobile_build_logs.zip)

How Has This Been Tested?
---
cargo test --all --all-features
nvm use v12.22.6 && ./node_modules/.bin/cucumber-js features/WalletFFI.feature
sh  mobile_build.sh

base_layer/wallet_ffi/Cargo.toml

@@ -7,7 +7,7 @@ version = "0.18.6"
 edition = "2018"
 
 [dependencies]
-tari_comms = { version = "^0.10", path = "../../comms", default-features = false}
+tari_comms = { version = "^0.10", path = "../../comms", features = ["c_integration"]}
 tari_comms_dht = { version = "^0.10", path = "../../comms/dht", default-features = false }
 tari_common_types = {path="../common_types"}
 tari_crypto = "0.11.1"

comms/Cargo.toml

@@ -30,7 +30,7 @@ lmdb-zero = "0.4.4"
 log = { version = "0.4.0", features = ["std"] }
 multiaddr = { version = "0.13.0" }
 nom = { version = "5.1.0", features = ["std"], default-features = false }
-openssl = { version = "0.10", features = ["vendored"] }
+openssl-sys = { version = "0.9.66", features = ["vendored"], optional = true }
 pin-project = "1.0.8"
 prost = "=0.8.0"
 rand = "0.8"
@@ -65,5 +65,6 @@ tempfile = "3.1.0"
 tari_common = { version = "^0.10", path = "../common", features = ["build"] }
 
 [features]
+c_integration = []
 avx2 = ["tari_crypto/avx2"]
 rpc = ["tower-make"]