RFR: 8357086: os::xxx functions returning memory size should return size_t [v8]

[Anton Artemov]

> Hi,
> 
> in this PR the output value type for functions which return memory are changed, namely:
> 
> 
> static julong available_memory(); --> static size_t available_memory();
> static julong used_memory(); --> static size_t used_memory();
> static julong free_memory(); --> static size_t free_memory(); 
> static jlong total_swap_space(); --> static ssize_t total_swap_space();
> static jlong free_swap_space(); --> static ssize_t free_swap_space(); 
> static julong physical_memory(); --> static size_t physical_memory(); 
> 
> 
> The changes are done so that the other parts of the code have minimal impact. 
> Tested in GHA and Tiers 1-4.

Anton Artemov has updated the pull request incrementally with two additional commits since the last revision:

 - 8357086: Changed returm type to struct.
 - 8357086: Return size_t from swap mem funcs, added checks.

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/25450/files
  - new: https://git.openjdk.org/jdk/pull/25450/files/2929f720..849d5466

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=25450&range=07
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=25450&range=06-07

  Stats: 200 lines in 20 files changed: 88 ins; 1 del; 111 mod
  Patch: https://git.openjdk.org/jdk/pull/25450.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25450/head:pull/25450

PR: https://git.openjdk.org/jdk/pull/25450