FS-6293: fix lua to build using automake, so it works right with srcdir, and avoids the linking to .a is not portable warning

build spandsp core elements as a conv lib so we can use didfferent cflags to include the right config.h when building those files

FS-6293: abandon xmlrpc-c build system entirely.  We can revist this when we try to pull this lib out of tree, in the mean time, this fixes a ton of problems.

Revert 6e818216, from FS-6287 as it breaks challenge to invites we don't come back and respond

use AM_SILENT_RULES where available and remove our hacks for quiet builds as they don't work very well and cause other build problems

We were calling switch_epoch_time_now() twice for no good reason.