Allow name-mangling for the mbedtls_free and mbedtls_calloc functions

According to the discussion in
rust-lang/rust-bindgen#1221 (comment),
the \u{1} is a hint to LLVM to avoid name-mangling but this might be required
on some platforms to link against the right name, e.g. on macOS.

mbedtls/src/alloc.rs

@@ -15,9 +15,9 @@ use core::mem::ManuallyDrop;
 use mbedtls_sys::types::raw_types::c_void;
 
 extern "C" {
-    #[link_name = concat!("\u{1}forward_mbedtls_free_", env!("RUST_MBEDTLS_METADATA_HASH"))]
+    #[link_name = concat!("forward_mbedtls_free_", env!("RUST_MBEDTLS_METADATA_HASH"))]
     pub(crate) fn mbedtls_free(n: *mut mbedtls_sys::types::raw_types::c_void);
-    #[link_name = concat!("\u{1}forward_mbedtls_calloc_", env!("RUST_MBEDTLS_METADATA_HASH"))]
+    #[link_name = concat!("forward_mbedtls_calloc_", env!("RUST_MBEDTLS_METADATA_HASH"))]
     pub(crate) fn mbedtls_calloc(n: mbedtls_sys::types::size_t, size: mbedtls_sys::types::size_t) -> *mut mbedtls_sys::types::raw_types::c_void;
 }