Fix --enable-opengles and --enable-opengles3 (#8749)

* qb: Fix OpenGLES build.

The gl core video driver requires at least OpenGLES 3 and
OpenGL 1 is not compatible with OpenGLES 2 or 3.

* travis: Test OpenGLES builds on linux.

.travis.yml

@@ -29,6 +29,10 @@ matrix:
       env: CXX_BUILD=1 CC=gcc-8 CXX=g++-8
     - compiler: gcc
       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
@@ -77,6 +81,14 @@ script:
      if [ -n "$DISABLE_MENU" ]; then
        ARGS="$ARGS --disable-menu"
      fi
+  - |
+     if [ -n "$ENABLE_GLES" ]; then
+       ARGS="$ARGS --enable-opengles"
+     fi
+  - |
+     if [ -n "$ENABLE_GLES3" ]; then
+       ARGS="$ARGS --enable-opengles3"
+     fi
   - ./configure $ARGS
   - |
      if [ -n "$C89_BUILD" ]; then

qb/config.libs.sh

@@ -351,6 +351,14 @@ fi
 if [ "$HAVE_OPENGL" = 'no' ] && [ "$HAVE_OPENGLES3" = 'no' ]; then
    die : 'Notice: OpenGL and OpenGLES3 are disabled. Disabling HAVE_OPENGL_CORE.'
    HAVE_OPENGL_CORE='no'
+elif [ "$HAVE_OPENGLES" != 'no' ] && [ "$HAVE_OPENGLES3" != 'yes' ]; then
+   die : 'Notice: OpenGLES2 is enabled. Disabling the OpenGL core driver.'
+   HAVE_OPENGL_CORE='no'
+fi
+
+if [ "$HAVE_OPENGLES" != 'no' ] || [ "$HAVE_OPENGLES3" != 'no' ]; then
+   die : 'Notice: OpenGLES is enabled. Disabling the OpenGL1 driver.'
+   HAVE_OPENGL1='no'
 fi
 
 if [ "$HAVE_ZLIB" = 'no' ]; then