minor leak in test

[bjodah]

Caught with asan, looks like buf* is never free'd (two occurrences)?

sundials-5.4.0/examples/nvector/test_nvector.c:

   5293:  buf = (realtype*) malloc((size_t)size);
   5356:  buf = (realtype*) malloc((size_t)size);

(adding free(buf) before return allows test to pass at least).

[balos1]

Fixed by v5.6.0.