There is a residual scar of an intermediate []byte copy because of the
signature of http.NewRequest, but this can be addressed later. The rtmp
interface needed alteration so that rtmp.Session satisfies io.Writer.
* Make C compilation arch-independent, including shared lib use and fix
for broken librtmp include install.
* Provide package-root level makefile for building C lib.
* Remove package global.
* Use Go-idiomatic naming for methods.
* Restucture flow to reduce indentation.
* Use []byte len in place of additional param.
* Use unix-idiomatic return status values.