runtime,cmd/compile: segfaults on loong64

[gopherbot]

#!watchflakes
post <- goarch == "loong64" && (log ~ `signal: segmentation fault \(core dumped\)` || log ~ `runtime error: invalid memory address or nil pointer dereference`)

Issue created automatically to collect these failures.

Example (log):

signal: segmentation fault (core dumped)

— watchflakes

[gopherbot]

Found new dashboard test flakes for:

#!watchflakes
default <- pkg == "golang.org/x/net/bpf" && test == ""

2023-11-08 19:35 linux-loong64-3a5000 net@fbaf4127 go@e1dc209b x/net/bpf (log)

signal: segmentation fault (core dumped)

— watchflakes

[gopherbot]

Sorry, but there were parse errors in the watch flakes script.
The script I found was:

#!watchflakes
post <- goarch == "loong64" && (log ~ signal: segmentation fault \(core dumped\)` || log ~ `runtime error: invalid memory address or nil pointer dereference`

And the problems were:

script:2.39: ~ requires backquoted regexp

See https://go.dev/wiki/Watchflakes for details.

— watchflakes

[bcmills]

(attn @golang/loong64)