8.1. Creating a Sub-Directory with a Different Configuration

To have a directory with its own separate configure script, first put it in the SUBDIRS variable of Makefile.am
Then use the AC_CONFIG_SUBDIRS macro in configure.in to configure them as separate sub-directories.
If a sub-directory inherits from the same subdirectory, then they will also be linked against all the shared libraries, which may not be desirable.