rts: enforce POSIX numeric locale for heap profiles (#17877)
As per issue #17877: use POSIX locale for LC_NUMERIC when writing to the profiling file, and restore when done.
So my commit:
- is either individually buildable or squashed
- has a commit message which describes what it does
- added source comments describing the change.
Not for that part, I'm afraid. I think the identifiers are explicit enough.
- adds a testcase to the testsuite
Not yet. Not sure how :-| See issue for why.
- replace this message with a description motivating your change