feat(core/rust): propagate bitcoin_only flag to Rust build

core/SConscript.firmware

@@ -665,7 +665,11 @@ def cargo_build():
         profile = '--release'
     else:
         profile = ''
-    return f'cd embed/rust; cargo build {profile} --target={RUST_TARGET} --target-dir=../../build/firmware/rust'
+    features = []
+    if BITCOIN_ONLY == "1":
+        features.append("bitcoin_only")
+
+    return f'cd embed/rust; cargo build {profile} --target={RUST_TARGET} --target-dir=../../build/firmware/rust --features "{" ".join(features)}"'
 
 rust = env.Command(
     target=RUST_LIBPATH,

core/SConscript.unix

@@ -617,7 +617,11 @@ def cargo_build():
         profile = '--release'
     else:
         profile = ''
-    return f'cd embed/rust; cargo build {profile} --target-dir=../../build/unix/rust'
+    features = []
+    if BITCOIN_ONLY == "1":
+        features.append("bitcoin_only")
+
+    return f'cd embed/rust; cargo build {profile} --target-dir=../../build/unix/rust --features "{" ".join(features)}"'
 
 rust = env.Command(
     target=RUST_LIBPATH,

core/embed/rust/Cargo.toml

@@ -6,6 +6,9 @@ edition = "2018"
 resolver = "2"
 build = "build.rs"
 
+[features]
+bitcoin_only = []
+
 [lib]
 crate-type = ["staticlib"]