contrib: vulkan-headers: detect current version

Automatically enable the headers, but detect the currently available header version with cppcheck since the pkgconfig file will actually detect the version of the loader.

cppcheck cannot understand the full header version, which was also not available before 1.3 anyway. Moreover, the major and minor versions are not defined directly, but instead either through cast or not at all (before 1.3), so we use the header guards defines and the VK_HEADER_VERSION for the last patch revision number.

Tested on linux with headers present and android with system header being obsolete.