Fix issue #2666

Currently, in master where latest tag is v0.12.0,
the build still says is it v0.11.0.

  [ben@centos bcc]$ cd build/
  [ben@centos build]$ cmake .. -DCMAKE_INSTALL_PREFIX=/usr
  -- Latest recognized Git tag is v0.11.0

The reason is the git_describe by default only checks
annotated tag while tag v0.12.0 is tagged through
github release process which just tags whatever the
top of the master.

Making git_describe to check all tags fixed the issue.

Signed-off-by: Yonghong Song <yhs@fb.com>