Macro duration_begin

macro_rules! duration_begin {
    ($category:expr, $name:expr $(, $key:expr => $val:expr)* $(,)?) => { ... };
}

Convenience macro for the duration_begin function.

Examples:

duration_begin!(c"foo", c"bar", "x" => 5, "y" => "boo");

const FOO: &'static CStr = c"foo";
const BAR: &'static CStr = c"bar";
duration_begin!(FOO, BAR, "x" => 5, "y" => "boo");