README / INSTALL should list requirments

[Torbjörn Andersson]

Ryan C. Gordon wrote:

 > bootstrap ran fine without FLAC here when I just tried it...can you
 > tell me what specifically is causing problems and/or which part of
 > bootstrap is failing?

I don't know what Max's problem with bootstrap is, but I know I always 
get a warning message about FLAC__stream_decoder_new. (I don't remember 
the exact wording, but I could look it up later if you want.)

It seems harmless enough though; I certainly don't have any problems 
building it afterwards, so I assumed it was autoconf stupidly assuming 
that anything that looks like AC_* has to be an unexpanded autoconf 
macro or some such.

Torbjörn