in order to always link with asan and ubsan libraries. Also
this is how the check-converter_example is compiled as well.

fixing the buffer overrun, as this fix was lost with this revert.

This reverts commit 615295a4.

Merging minor security fix (#318)

The function `SET_OF__encode_sorted` stored the working element buffer
in a static variable. If called recursively (that is, when performing
encoding of a SET containing another SET) the outermost element buffer
is therefore clobbered by the innermost call.

This causes a SEGV on continuation of the outermost call.

Bug found during testing of [https://github.com/surevine/spiffing Spiffing],
fix verified with the same test suite.

zeroed repeat. Fix takes value of repeat.

Add aper encoder for SET_OF