RFR: 8313882: Fix -Wconversion warnings in runtime code [v4]

[Coleen Phillimore]

> Here are fixes to silence -Wconversion warnings in runtime code.  Use direct cast for 64 bit int to double, otherwise default to checked_cast<>.  I changed the declaration of _held_monitor_count and _jni_monitor count to intx to fix cascade of warnings coming from this.
> 
> src/hotspot/share/runtime/synchronizer.cpp:1802:41: warning: conversion from 'intx' {aka 'long int'} to 'int' may change value [-Wconversion]
>  1802 |     _thread->dec_held_monitor_count(rec + 1);
>       |                                     ~~~~^~~
> 
> Tested with tier1-4 on linux-x64-debug and windows-x64-debug and tier1 on Oracle supported platforms.

Coleen Phillimore has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains 17 additional commits since the last revision:

 - Merge branch 'master' into runtime-conversion
 - Change Arguments::parse_uintx to parse_uint and callers.
 - Dean's and Patricio's suggested changes.
 - Make bytecode.hpp index() functions return u2 not long.
 - Fix jvmci for held_monitor_count type.
 - Fix format strings for monitor_counts and fix arguments.cpp differently.
 - Fix gtests
 - Fix asserted files in runtime with one warning.
 - Fix signature.cpp
 - Fix continuationFreezeThaw.cpp
 - ... and 7 more: https://git.openjdk.org/jdk/compare/e4063a36...f4961655

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/15177/files
  - new: https://git.openjdk.org/jdk/pull/15177/files/1af1cfe5..f4961655

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=15177&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=15177&range=02-03

  Stats: 7972 lines in 425 files changed: 2632 ins; 2838 del; 2502 mod
  Patch: https://git.openjdk.org/jdk/pull/15177.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15177/head:pull/15177

PR: https://git.openjdk.org/jdk/pull/15177