Apply GLSL patch for areaScaleFragmentShader

Thanks to Lubos Lunak

Change-Id: I9bb72e1a5b11102963481dac7c11ab4a9fe90b0b
Signed-off-by: Chris Sherlock <chris.sherlock79@gmail.com>
Reviewed-on: https://gerrit.libreoffice.org/14095

vcl/opengl/areaScaleFragmentShader.glsl

@@ -7,6 +7,12 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
  */
 
+#version 120
+#if __VERSION__ < 130
+int min( int a, int b ) { return a < b ? a : b; }
+float min( float a, float b ) { return a < b ? a : b; }
+#endif
+
 /* TODO Use textureOffset for newest version of GLSL */
 
 uniform sampler2D sampler;