Changed cmake_minimum_required VERSION to 2.8.12
Changed cmake_minimum_required VERSION to 2.8.12

Newer CMake binaries started to generate a warning if
'cmake_minimum_required' 'VERSION' is less than '2.8.12'.
Increased this 'VERSION' to suppress the warning.

percona/PerconaFT,percona/PerconaFT,percona/PerconaFT,percona/PerconaFT