Update clap-sys with optional function pointers

None of these function pointers are allowed to be null, yet even the
official `clap-helpers` do this. This new `clap_call!()` macro asserts
that a pointer is non-null before calling it.

Cargo.toml

@@ -67,7 +67,8 @@ atomic_refcell = "0.1"
 backtrace = "0.3.65"
 bitflags = "1.3"
 cfg-if = "1.0"
-clap-sys = "0.1"
+# TODO: Switch back to the crates.rs version once the debug prints are in a released version
+clap-sys = { git = "https://github.com/glowcoil/clap-sys.git", rev = "efc0940651c3a57a3f9402bf3798cda9a7f7fc87" }
 crossbeam = "0.8"
 lazy_static = "1.4"
 log = { version = "0.4", features = ["std", "release_max_level_info"] }