ZJIT: Widen profiling window from 5 to 25 observations

Increase DEFAULT_NUM_PROFILES so the interpreter collects more type
observations before compilation. The wider window gives better type
coverage for cold paths and polymorphic call sites, improving the
quality of generated code on first compilation.

Author: nmeans

zjit/src/options.rs

@@ -7,7 +7,7 @@ use crate::stats::Counter;
 use std::collections::HashSet;
 
 /// Default --zjit-num-profiles
-const DEFAULT_NUM_PROFILES: NumProfiles = 5;
+const DEFAULT_NUM_PROFILES: NumProfiles = 25;
 pub type NumProfiles = u32;
 
 /// Default --zjit-call-threshold. This should be large enough to avoid compiling