object_test: Removed 'obj->ref_cnt == 0' checks.

They generate unnecessary noise in LLVM's AddressSanitizer runs.
Fixed memory errors identified by LLVM's AddressSanitizer.

Test performed as:

  ./configure CC=clang \
      CFLAGS="-O0 -g -fsanitize=address -fno-omit-frame-pointer" \
      LDFLAGS=-fsanitize=address
  make clean all test

See also http://clang.llvm.org/docs/AddressSanitizer.html
t/cibuild.sh, .travis.yml: Do an AddressSanitizer run as well.

Passing additional build flags as CICFLAGS and CILDFLAGS.