[PATCH v3 03/15] Read CTF by the ctf target

[Doug Evans]

Doug Evans writes:
 > Is there a compelling need for with-babeltrace-{include,lib}?
 > We don't have with-expat-{include,lib} for example.
 > I think we should punt on them for now if there's no real need for them.

Running ./configure --help I see expat provides a different means
for specifying the location.

  --with-expat            include expat support (auto/yes/no)
  --with-libexpat-prefix[=DIR]  search for libexpat in DIR/include and DIR/lib
  --without-libexpat-prefix     don't search for libexpat in includedir and libdir

Ideally we should be consistent.

IIUC, expat support does this:

  AC_LIB_HAVE_LINKFLAGS([expat], [], [#include "expat.h"],
			[XML_Parser p = XML_ParserCreate (0);])

and that drags in the rest of the support from src/config/lib*.m4.
[One needn't necessarily do the same thing, but I think the end result,
as far as configure options goes, should be the same.]