Fix shaders generation on IMG GPUs.

const char* gVS_Header_Uniforms =

        "uniform mat4 transform;\n";

const char* gVS_Header_Uniforms_IsPoint =

        "uniform float pointSize;\n";

        "uniform mediump float pointSize;\n";

const char* gVS_Header_Uniforms_HasGradient[3] = {

        // Linear

        "uniform mat4 screenSpace;\n",

};

const char* gVS_Header_Uniforms_HasBitmap =

        "uniform mat4 textureTransform;\n"

        "uniform vec2 textureDimension;\n";

        "uniform mediump vec2 textureDimension;\n";

const char* gVS_Header_Varyings_HasTexture =

        "varying vec2 outTexCoords;\n";

const char* gVS_Header_Varyings_HasBitmap =