[Dvipng] [patch] configure flags for t1lib and freetype

[Samuli Suominen]

In order to make dvipng a bit more source-based distribution friendly to
allow package manager to control the features of the package, I've wrote
a quick patch to add flags:

--enable/--disable-freetype
--enable/--disable-t1lib

To the configure.ac file. With the patch if no flags are specified, the
current behavior of auto-detect is used.

Patch:

http://bugs.gentoo.org/attachment.cgi?id=228543

Bug:

http://bugs.gentoo.org/show_bug.cgi?id=316329

Would be nice to see this, or something similar applied in upstream
dvipng so we don't have to carry the patch in the distro...

Thanks, Samuli