pcre: drop package

This package is no longer actively maintained as it reached
End-of-Life. [1] All new projects should use PCRE2.

OpenWrt wants to be minimalistic and we migrated many packages
from PCRE to PCRE2 huge thanks belong to @Ansuel (Christian Marangi),
who worked with several open-source projects to migrate it to PCRE2 [2].
This means that on routers, we don't need to have installed two libraries
(pcre and pcre2) side by side.

[1] https://www.pcre.org/
[2] openwrt#22006

Fixes: openwrt#22006
Signed-off-by: Josef Schlehofer <[email protected]>