Fix the OpenGLES3 build.

This depends on HAVE_EGL.

Revert "Remove this Travis test for now"

This reverts commit 678089c2de.

.travis.yml

@@ -31,6 +31,8 @@ matrix:
       env: DISABLE_MENU=1 CC=gcc-8 CXX=g++-8
     - compiler: gcc
       env: ENABLE_GLES=1 CC=gcc-8 CXX=g++-8
+    - compiler: gcc
+      env: ENABLE_GLES=1 ENABLE_GLES3=1 CC=gcc-8 CXX=g++-8
     - compiler: clang
       env: CC=clang-6.0 CXX=clang++-6.0
     - compiler: clang

qb/config.libs.sh

@@ -348,6 +348,7 @@ else
    HAVE_OPENGL='no'
 fi
 
+check_enabled EGL OPENGLES3 OpenGLES3 'EGL is' false
 check_enabled OPENGL CG Cg 'OpenGL is' false
 check_enabled OPENGL OSMESA osmesa 'OpenGL is' false
 check_enabled OPENGL OPENGL1 OpenGL1 'OpenGL is' false