fixed some compilation errors

Author: Joshua Mir

Cargo.lock

@@ -20,6 +20,7 @@ sp-runtime = { version = "2.0.0-rc4", default-features = false }
 sp-std = { version = "2.0.0-rc4", default-features = false }
 sp-io = { version = "2.0.0-rc4", default-features = false }
 sp-core = { version = "2.0.0-rc4", default-features = false }
+sp-arithmetic = { version = "2.0.0-rc4", default-features = false }
 rand_chacha = { version = "0.2", default-features = false }
 brotli = { version = "3.3.0", default-features = false }
 
@@ -36,6 +37,7 @@ std = [
 	"frame-system/std",
 	"sp-io/std",
 	"sp-core/std",
+	"sp-arithmetic/std",
 	"sp-std/std",
 	"brotli/std"
 ]