Log Message:
Updated libepoxy to 1.4.

This is a new stable release.

Major changes for 1.4 are:

    Epoxy can now build with MSVC versions prior to 2013; we still recommend \ 
using a recent, C99-compatible compiler, like MSVC 2015 [Chun-wei Fan]
    When used under X11, Epoxy now attempts to handle the cases where the GLX \ 
extension is not built or not available [Yaron Cohen-Tal]
    GLX can now be enabled and disabled at configuration time; this allows \ 
building Epoxy with GLX on macOS, and allows building Epoxy without GLX on \ 
embedded platforms
    Epoxy now exposes API that lets dependent projects safely check if platform \ 
API like GLX and EGL is available at run time
    EGL support has been improved on Windows, and made more resilient on other \ 
platforms [Yaron Cohen-Tal, Adam Jackson]
    Epoxy supports building with the Meson build system, which has Ninja, Visual \ 
Studio, and XCode backends
    Epoxy can generate its API reference using Doxygen (currently only available \ 
on Meson builds)
    The GL registry has been updated with the latest version of the API \ 
references provided by Khronos; Epoxy now supports the API introduced by OpenGL \ 
4.5