input/Plugin: copy protocols() to stack before using it

Fixes regression by commit 015cbff93d causing a crash bug because the
iterators of two different temporaries were used.

src/input/InputPlugin.cxx

@@ -33,7 +33,8 @@ InputPlugin::SupportsUri(const char *uri) const noexcept
 			if (StringStartsWithIgnoreCase(uri, *i))
 				return true;
 	} else {
-		return std::any_of(protocols().begin(), protocols().end(), [uri](const auto &schema)
+		const auto p = protocols();
+		return std::any_of(p.begin(), p.end(), [uri](const auto &schema)
 			{ return StringStartsWithIgnoreCase(uri, schema.c_str()); } );
 	}
 	return false;