give-back pcre3

[Helmut Grohne <helmut@subdivi.de>]

Hi,

The last pcre3 upload failed to build on most architectures including
amd64. I looked into the problem today and figured that a simple rebuild
would "fix" the problem. I presume that this is due to a gcc-8 upload
since. A give-back will only work around the issue at best, and #904506
is still there. Still it will remove the urgency. Presently the pcre3
source/binary version skew breaks bootstrap QA as pcre3 builds
transitively essential packages. So please consider giving it back to
help with QA. If it fails again, I'll look into NMUing.

Helmut