patch 9.0.1842: Need more accurate profiling

Problem:  Need more accurate profiling
Solution: Improve profiling results

closes: #12192

Reduce overhead of checking if a function should be profiled,
by caching results of checking (which are done with regexp).

Cache uf_hash for uf_name in ufunc_T.

Cache cleared when regexps are changed.

Break at first match for has_profiling lookup.

Signed-off-by: Christian Brabandt <cb@256bit.org>
Co-authored-by: Ernie Rael <errael@raelity.com>

src/structs.h

@@ -1823,6 +1823,7 @@ struct ufunc_S
 # ifdef FEAT_PROFILE
     int		uf_profiling;	// TRUE when func is being profiled
     int		uf_prof_initialized;
+    hash_T	uf_hash;	// hash for uf_name when profiling
     // profiling the function as a whole
     int		uf_tm_count;	// nr of calls
     proftime_T	uf_tm_total;	// time spent in function + children