Do not lose one page of scrollback buffer after CLEAR.
Merge branch 'master' of https://github.com/ScrollZ/ScrollZ

* 'master' of https://github.com/ScrollZ/ScrollZ:
  Fix a silly omission so ScrollZ can be compiled with llvm/clang.
  Fix some compiler warnings to make SteelyDan happy.
Fix configure on FreeBSD 10.
Fix configure on FreeBSD 10.