Regular Expression used to test if a string is a proper_slice.

Encodes a C string.

On Unix based systems, we need to supply dlopen with RTLD_GLOBAL but Deno.dlopen does not support passing that flag. So we'll open libc and use its dlopen to open with RTLD_LAZY | RTLD_GLOBAL to allow subsequently loaded shared libraries to be able to use symbols from Python C API.