update to doc/Makefile.am
update to doc/Makefile.am

The fdl and gpl texinfo files were not being specified as dependencies
correctly.  Also, the extra_dist variable was adjusted to only specify
the figures directory since automake will distribute everything in a
directory if the directory is listed in extra_dist.

These changes are imported from the opentts doc/Makefile.am

Reviewed-by: Christopher Brannon <cmbrannon79@gmail.com>

Modified by Chris Brannon: fixed rebase conflicts.
Reviewed-by: Andrei Kholodnyi <8ed355542eeb21dc16259915650192a25bd4bf1a@gmail.com>

razr/speechd,razr/speechd,razr/speechd,razr/speechd