fix-gnulib: Improvements for program-only packages.

fix-gnulib: Improvements for program-only packages.

When building a program, we do not generally need the Gnulib symbol
renaming support and we do not need to build a libtool convenience
library (which typically takes twice as long).

It appears the object dependencies are incomplete when not using
libtool with Gnulib, so fix that, and add a new "program" mode which
omits the default call to GLSYM_PREFIX (and thus the DX_EXPORTED_SH
machinery does not not pulled in).

In all cases, switch noinst_(LT)LIBRARIES to EXTRA_(LT)LIBRARIES
which should have no negative impact -- but a program can link in
$(gnulib_objects) instead of the library to save a build step and
possibly increase opportunity for parallelism.

When using libtool, library mode is the default, otherwise program
mode is the default.  The script can be forced one way or the other
based on command-line options.