Tup unnecessarily depends on libpcre.so.3

[typeless]

I want to create a Yocto recipe for Tup.
To reduce build time and complexity, I want to ensure Tup has minimal dependencies.
I expect libpcre to be statically linked with the self-contained pcre package.
But when building Tup, readelf -d seems to still show libpcre.3.so.3 as a dependent shared lib.

I use the master branch and build it using bootstrap-ldpreload.sh and CONFIG_TUP_SERVER=ldpreload in tup.config on Ubuntu Linux.

[typeless]

Looking into the build scripts inside, I realized that can be configured by CONFIG_TUP_USE_SYSTEM_PCRE=n. in tup.config.