Bump libepoxy to 1.3

1.3 has been released in 2015 which is sufficiently old enough.

CMakeLists.txt

@@ -173,7 +173,7 @@ set_package_properties(EGL PROPERTIES
     PURPOSE "Required to build KWin with EGL support"
 )
 
-find_package(epoxy)
+find_package(epoxy 1.3)
 set_package_properties(epoxy PROPERTIES
     DESCRIPTION "libepoxy"
     URL "https://github.com/anholt/libepoxy"

src/platformsupport/scenes/opengl/openglbackend.cpp

@@ -18,17 +18,6 @@
 #include <epoxy/gl.h>
 #include <unistd.h>
 
-// HACK: workaround for libepoxy < 1.3
-#ifndef GL_GUILTY_CONTEXT_RESET
-#define GL_GUILTY_CONTEXT_RESET 0x8253
-#endif
-#ifndef GL_INNOCENT_CONTEXT_RESET
-#define GL_INNOCENT_CONTEXT_RESET 0x8254
-#endif
-#ifndef GL_UNKNOWN_CONTEXT_RESET
-#define GL_UNKNOWN_CONTEXT_RESET 0x8255
-#endif
-
 namespace KWin
 {