Improve Endian Bitness for sasindex

Additional clean-up for sasindex key handling. Added a union and functions
to correctly handle non-pointer keys for 32-bit and Little-Endian. Updated
sasindex_t.c to add sasindex_print_node_uint, sasindex_print_uint,
sassim_index_test2 to directly test the new function for uint64.
More Improvements to Endian Bitness for sasindex

Additional SASIndex patches that apply on top of the previous patch below.

I found a number of bugs that impact large indexes (129+) where node split and
0/NULL keys where confusing SASIndexEnum. Added a new test case to sasindex_t.c
to expose/debug this. With these patches it now now handles indexes with
1000000+ keys.

Added a new test (sasindex_tt.c) to measure performance and allow
profiling/tuning of Index performance.

I changed ./src/Makefile.am so will need to autoreconf and commit the updatedi
configure files to github.

Should look at the SASStringBTree implementation to see if similar bugs are
there. Note that StringBTree does not currently handle null strings as keys,
so may not be as large and issue.
Cleaning up compiler warnings