libs: Move cstr!() into its own crate
Make the macro host_supported, for unittests.
This overshadows the homonymous crate from crates.io [1] but importing
and depending on an external crate for <10 lines of code seems overkill.
[1]: https://crates.io/crates/cstr
Bug: 308694211
Test: atest libcstr.tests
Test: m libcstr
Test: m pvmfw_bin rialto_bin vmbase_example_bin
Change-Id: If1bf37034fc004a380b3ba528b9d76393a865d3e
diff --git a/vmbase/src/fdt.rs b/vmbase/src/fdt.rs
index 537ca03..4101f7e 100644
--- a/vmbase/src/fdt.rs
+++ b/vmbase/src/fdt.rs
@@ -14,8 +14,8 @@
//! High-level FDT functions.
-use crate::cstr;
use core::ops::Range;
+use cstr::cstr;
use libfdt::{self, Fdt, FdtError};
/// Represents information about a SWIOTLB buffer.