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/bionic.rs b/vmbase/src/bionic.rs
index f8db1fe..a049616 100644
--- a/vmbase/src/bionic.rs
+++ b/vmbase/src/bionic.rs
@@ -22,11 +22,12 @@
use core::str;
use crate::console;
-use crate::cstr;
use crate::eprintln;
use crate::rand::fill_with_entropy;
use crate::read_sysreg;
+use cstr::cstr;
+
const EOF: c_int = -1;
const EIO: c_int = 5;