RFR: 8183569: Remove duplicated flag limits in parse_xss and globals.hpp [v2]

[Ioi Lam]

> We have the following in Arguments::parse_xss():
> 
>   const julong min_ThreadStackSize = 0;
>   const julong max_ThreadStackSize = 1 * M;
>   const julong min_size = min_ThreadStackSize * K;
>   const julong max_size = max_ThreadStackSize * K;
> 
> which duplicates the min/max range specified in globals.hpp:
> 
>   product_pd(intx, ThreadStackSize, \
>           "Thread Stack Size (in Kbytes)") \
>           range(0, 1 * M) \
> 
> I added an API to query the min/max range of a flag, so parse_xss can be rewritten as
> 
>   const JVMTypedFlagLimit<intx>* limit = 
>     JVMFlagLimit::get_range_at(FLAG_MEMBER_ENUM(ThreadStackSize))->cast<intx>();
>   const julong min_size = limit->min() * K;
>   const julong max_size = limit->max() * K;

Ioi Lam has updated the pull request incrementally with one additional commit since the last revision:

  use macros to simplify assert_compatible_type; restore code in parse_xss so the comments make sense

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/2688/files
  - new: https://git.openjdk.java.net/jdk/pull/2688/files/0386a37e..8c4b5cd9

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=2688&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=2688&range=00-01

  Stats: 48 lines in 3 files changed: 13 ins; 30 del; 5 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2688.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2688/head:pull/2688

PR: https://git.openjdk.java.net/jdk/pull/2688