Makefile.am:

* Don't use @VAR@, use $(VAR). Autoconf's AC_SUBST provides us the Make
   variable, it allows overriding the value at the command line, and
   (notably) it avoids a Make parse error in the libxml2_la_LDFLAGS
   assignment when @MODULE_PLATFORM_LIBS@ is empty

* Changed how the THREADS_W32 mechanism switches the build between
   testThreads.c and testThreadsWin32.c as appropriate; using AM_CONDITIONAL
   allows this to work cleanly and plays well with dependencies

* testapi.c should be specified as BUILT_SOURCES

* Create symlinks to the test/ and result/ subdirs so that the runtests
   target is usable in out-of-source-tree builds

* Don't do MAKEFLAGS+=--silent as this is not portable to non-GNU Makes

* Fixed incorrect find(1) syntax in the "cleanup" rule, and doing "rm -f"
   instead of just "rm" is good form

* (DIST)CLEANFILES needed a bit more coverage to allow "make distcheck" to
   pass

configure.in:

* Need AC_PROG_LN_S to create te...