Correct the counting of the number of arguments

Clippy rightfully complains, that a `.skip(0)` does not make sense and
likely should have been a `.skip(1)`. This commit changes it, but it is
strange, that both versions work and pass the test suite. Therefore this
is a separate commit, so it could be reverted if necessary.

src/main.rs

@@ -95,7 +95,7 @@ fn display_stack_trace(msg: &str, stack: &valgrind::xml::Stack) {
 fn main() {
     panic::replace_hook();
 
-    let number_of_arguments = || env::args_os().skip(0).count();
+    let number_of_arguments = || env::args_os().skip(1).count();
     let help_requested = || env::args_os().any(|arg| arg == "--help" || arg == "-h");
     let is_cargo_subcommand = || env::args_os().nth(1).map_or(false, |arg| arg == "valgrind");
     if number_of_arguments() == 0 || help_requested() {