runtime/testdata: fix for C23 nullptr keyword
src/runtime/testdata/testprogcgo/threadprof.go contains C code with a
variable called nullptr. This conflicts with the nullptr keyword in
the C23 revision of the C standard (showing up as gccgo test build
failures when updating GCC to use C23 by default when building C
code).
Rename that variable to nullpointer to avoid the clash with the
keyword (any other name that's not a keyword would work just as well).
Change-Id: Ida5ef371a3f856c611409884e185c3d5ded8e86c
GitHub-Last-Rev:
2ec464703be0507a67a077741789a37511d197e4
GitHub-Pull-Request: golang/go#69927
Reviewed-on: https://go-review.googlesource.com/c/go/+/620955
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>