Gainless, 2012, and Ivqcl on Hydrogenaudio reported and helped
identify an issue where opusdec was adding a click in 44.1kHz
output. This was becaue the loop needed to feed the resampler
for >1024 sample input wasn't accounting for the preskip and
was putting too many samples into the resampler on the first
packet. Eventually the output got ahead of the container
granpos and the decoder dropped some samples to catch up.

For 1 second pages, the opusenc default, dropped samples
happened just about at the 1 second mark.

more than one page of pre-skip.

When build against a static libopus (built without -fPIC)
the final link with -fPIE will fail. It's convenient to
be able to do this for building against an uninstalled libopus.

Unfortunately this involves moving the -fPIE check until
after the library checks, so we can add it to the link
line before testing. We also have to reference a libopus
symbol to keep the linker from skipping the dependency.

This creates a hard failure in cases that would have been
a silent failure before which might have been hiding other
bugs, so it needs testing.

Also adds so paranoia to avoid infinite loops, even if the
caller of audio_write is stupid.

This reverts commit fd3abf6b.

'cause it didn't actually work.

Also make the opusdec help show --quiet.

opus_header.[ch] were changed to using the ogg types rather than
the opus ones in order to facilitate copying them into other
packages.