Add rust musl arm and arm64 toolchains

Add rust toolchain configurations for arm-linux-musleabihf and
aarch64-linux-musl.

Bug: 236052820
Test: builds with linux musl arm64 host cross configured
Change-Id: Icfa73a75eac710e955f71a073cb4b7bb1cdfcc7a
diff --git a/rust/config/Android.bp b/rust/config/Android.bp
index 7757c79..ba40cb0 100644
--- a/rust/config/Android.bp
+++ b/rust/config/Android.bp
@@ -11,6 +11,7 @@
     ],
     srcs: [
         "arm_device.go",
+        "arm_linux_host.go",
         "arm64_device.go",
         "global.go",
         "lints.go",