[11u] RFR(S): 8250635 backport: MethodArityHistogram should use Compile_lock in favour of fancy checks

[Schmidt, Lutz]

Dear Community, 

I would appreciate receiving reviews for this downport change. It is a small change in one file only. Unfortunately, it did not apply clean. 

Original bug:    https://bugs.openjdk.java.net/browse/JDK-8250635 
Downport webrev: https://cr.openjdk.java.net/~lucy/webrevs/8250635.11u.01/ 

Tests:
SAP's internal build and test farm. Results pending. 

Thank you!
Lutz