Function __program_invocation_name 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn __program_invocation_name() -> *mut *mut c_char

Get the name used to invoke the program, similar to argv[0].

This provides the basis for the C-facing macro definition of program_invocation_name, and should not be used directly.

The program_invocation_name variable is a GNU extension.