Replace "positive" with "non-negative"

The latter is less ambiguous.

Co-authored-by: Vadim Petrochenkov <[email protected]>

Author: ShE3py

compiler/rustc_session/src/options.rs

@@ -385,7 +385,7 @@ mod desc {
         "`all` (default), `except-unused-generics`, `except-unused-functions`, or `off`";
     pub const parse_instrument_xray: &str = "either a boolean (`yes`, `no`, `on`, `off`, etc), or a comma separated list of settings: `always` or `never` (mutually exclusive), `ignore-loops`, `instruction-threshold=N`, `skip-entry`, `skip-exit`";
     pub const parse_unpretty: &str = "`string` or `string=string`";
-    pub const parse_treat_err_as_bug: &str = "either no value or a positive number";
+    pub const parse_treat_err_as_bug: &str = "either no value or a non-negative number";
     pub const parse_trait_solver: &str =
         "one of the supported solver modes (`classic`, `next`, or `next-coherence`)";
     pub const parse_lto: &str =