If the generated header files are included in the distribution, a build
outside of the source directory will use them. For machine-specific files,
this generates the wrong result (fcarch.h). Leaving them out of the
distribution forces them to be built.
Using a simple shell script that processes the public headers, two header
files are constructed that map public symbols to hidden internal aliases
avoiding the assocated PLT entry for referring to a public symbol.
A few mistakes in the FcPrivate/FcPublic annotations were also discovered
through this process
Map existing architecture signature to short architecture name
at build time. This architecture name is (as yet) unused, but will be used
to build per-architecture cache files with names made unique by including
the architecture name. The auto-detected architecture name can be overridden
with the --with-arch=ARCH configure option.