Cleanup the usage of the SQLITE_DISABLE_INTRINSIC compile-time option.

Cleanup the usage of the SQLITE_DISABLE_INTRINSIC compile-time option.
Remove the SQLITE_RUNTIME_BYTEORDER compile-time option.  Use
-DSQLITE_BYTEORDER=0 instead.  Fix a bug in R-Tree that occurs when compiling
on a known little-endian machine without the use of intrinsic byteswapping
functions.

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