Previously it output to an ordinary char buffer, and returned the
number of bytes it had written. But three out of the four call sites
immediately chucked the resulting bytes into a BinarySink anyway. The
fourth, in windows/unicode.c, really is writing into successive
locations of a fixed-size buffer - but we can make that into a
BinarySink too, using the buffer_sink added in the previous commit.
So now encode_utf8() is renamed put_utf8_char, and the call sites all
look simpler than they started out.
Now that the new CMake build system is encouraging us to lay out the
code like a set of libraries, it seems like a good idea to make them
look more _like_ libraries, by putting things into separate modules as
far as possible.
This fixes several previous annoyances in which you had to link
against some object in order to get a function you needed, but that
object also contained other functions you didn't need which included
link-time symbol references you didn't want to have to deal with. The
usual offender was subsidiary supporting programs including misc.c for
some innocuous function and then finding they had to deal with the
requirements of buildinfo().
This big reorganisation introduces three new subdirectories called
'utils', one at the top level and one in each platform subdir. In each
case, the directory contains basically the same files that were
previously placed in the 'utils' build-time library, except that the
ones that were extremely miscellaneous (misc.c, utils.c, uxmisc.c,
winmisc.c, winmiscs.c, winutils.c) have been split up into much
smaller pieces.
