Remove frexp_modf custom OverloadSet impl.

Author: jimblandy

naga/src/proc/builtins/frexp_modf.rs

@@ -8,7 +8,6 @@ mod scalar_set;
 mod regular;
 
 mod anyoverloadset;
-mod frexp_modf;
 mod list;
 mod lists;
 mod one_bits_iter;