cmake.bbclass: Make it work with ccache

cmake.bbclass: Make it work with ccache

This can make the following recipes work with cmake:
cmake libdnf libcomps librepo createrepo-c llvm dnf libsolv assimp waffle
libjpeg-turbo taglib libproxy libical

And the following 3 recipes don't:
webkitgtk vulkan piglit
Now cmake.bbclass doesn't disble ccache any more, disable it in the recipes if
needed.

Signed-off-by: Robert Yang <liezhi.yang@windriver.com>