I tried to install Qt 5.10.0 from the sources with support of the Vulkan API. During the configuration Vulkan was well detected on my system and all the QVulkan* classes and header were installed except for "qvulkanfunctions.h" (which is quite essential).
I solved the problem by retrieved the file from the temporary build directory and I copied it manually in the install directory.
I hope I did not miss something during the installation so here is the list of command I used :
$ mkdir <buildDir>$ cd <buildDir>$ <srcDir>/configure -prefix <installDir> -opensource -debug -I/<vulkanSdkDir>/include
$ make install
Thanks for your attention,