[Chapel Merge] Detect RISC-V 64-bit Linux

Branch: refs/heads/main
Revision: 008f7d4619883862334a848675abb7b5a5120513
Author: insertinterestingnamehere
Link: Detect RISC-V 64-bit Linux by insertinterestingnamehere · Pull Request #28365 · chapel-lang/chapel · GitHub
Log Message:
Detect RISC-V 64-bit Linux (#28365)

[developed by @insertinterestingnamehere, reviewed by me and @jabraham17]

The current version of the platform detection script falls back to
32-bit linux for unrecognized architectures. This patch allows it to
properly detect 64-bit risc-v.

Compare: Comparing 2e989f33d292179ed4a290180580cc62746da41c...ff04437c189c0dab791380945254c410b6eb0876 · chapel-lang/chapel · GitHub

Diff:
M util/chplenv/chpl_platform.py
https://github.com/chapel-lang/chapel/pull/28365.diff