http: optimize HTTP request thread we don't need a mutex at all, in fact all we need is an atomic boolean to signify whether the thread is cancelled. curl options are now for the most part handled by a separate function to keep them in sync between non-threaded and threaded implementations

include/
include/utf8proc.h
lib/
lib/libutf8proc.a
lib/libutf8proc.so -> libutf8proc.so.3.0.0
lib/libutf8proc.so.2 -> libutf8proc.so.3.0.0
lib/libutf8proc.so.3.0.0
lib/pkgconfig/
lib/pkgconfig/libutf8proc.pc