bug#51235: resolve old FIXME in PCRE implementation to allow more than 1 expression

[Paul Eggert]

On 10/16/21 12:00 AM, Carlo Arenas wrote:
> With this patch, multiple expressions (from -e or -f) are now
> acceptable with -P for easier side by side comparison with the other
> supported engines.

Surely this mishandles shell commands like this one:

grep -P '[
a]'

which should be an error, but with that patch would not be an error.