switch drconfiglib and drinjectlib to be static instead of shared

The loader on Android (xref #1701) does not support DT_RUNPATH. We could try to swap in the older DT_RPATH, or we could switch drconfiglib and drinjectlib to be static instead of shared.

If we change drconfiglib and drinjectlib to be static, old frontends might break, so better to have two different libs (shared + static) like DRMF does? OTOH, these libs are BSD unlike DRMF, and changing will only break someone who built their own frontend but doesn't ship their own DR, which seems unlikely.

Much simpler to be static: avoid all the add_rel_rpaths() and the Mac #1375 INSTALL_NAME_DIR stuff, and all the copying of libs on Windows. drfrontendlib and drdecodelib are already static.