MFH: r566474

devel/newt: does not register shared libs

pkg info -b newt does not show any shared libraries despite the port installing
one.

The framework uses the output of readelf -d to know if the library has a SONAME
and this ports does not add a SONAME if it does not detect the GNU linker. Then,
the resulting package does not register any shared libraries.

• Patch configure.ac to learn and detect LLVM linker so it adds the SONAME to the library.
• Add USE_LDCONFIG (portlint wrongly complains about not installing shared libs)

PR: 253712
Submitted by: masamory7@gmail.com