Change backend struct option to li_dbcachewsync.

Remove AC_GCC_TRADITIONAL check.  Likely to cause more harm than good.

Added ac/stdarg.h and updated liblber encode/decode to use it.

modify apps to use TOLOWER/TOUPPER macros to ensure isupper/islower is
called when approprate.

Now require --enable-x-compile if cross compiling.
Add tests for threadsafe/reentrant functions.
Add tests for setconcurrency functions.