shader: Enable GL_ARB_texture_cube_map_array in shader on gles 3.1 host

The extension is part of GLSL 320 es, but must be enabled manually for a
gles 3.1 host. Closes: #32

Signed-off-by: Gert Wollny <gert.wollny@collabora.com>
Reviewed-by: Dave Airlie <airlied@redhat.com>

src/vrend_shader.c

@@ -4089,6 +4089,8 @@ static char *emit_header(struct dump_ctx *ctx, char *glsl_hdr)
             STRCAT_WITH_RET(glsl_hdr, "#extension GL_OES_sample_variables : require\n");
          if (ctx->shader_req_bits & SHADER_REQ_GPU_SHADER5)
             STRCAT_WITH_RET(glsl_hdr, "#extension GL_OES_gpu_shader5 : require\n");
+         if (ctx->shader_req_bits & SHADER_REQ_CUBE_ARRAY)
+            STRCAT_WITH_RET(glsl_hdr, "#extension GL_OES_texture_cube_map_array : require\n");
       }