declare project as C-only to avoid looking for CXX related symbols (#113

)

* Squashed 'deps/ccommon/' changes from bb298bc..05c6e1e

05c6e1e explicitly make ccommon a C project to avoid checking for CXX related variables

git-subtree-dir: deps/ccommon
git-subtree-split: 05c6e1e

* make project explicitly C-only

Merge pull request #112 from thinkingfish/fix_check

Fix build without the presence of libcheck

fix broken link in README.md