blitter: Add a FS shader for MSAA depth blits

This will be needed because on GLES blits to a MS surface need to
use the GL fallback path.

Signed-off-By: Gert Wollny <gert.wollny@collabora.com>
Reviewed-by: Gurchetan Singh <gurchetansingh@chromium.org>

src/vrend_blitter.h

@@ -111,8 +111,16 @@
    "   gl_FragDepth = float(texelFetch(samp, %s(tc%s), int(tc.z)).x);\n" \
    "}\n"
 
+#define FS_TEXFETCH_DS_MSAA_BODY_GLES                                     \
+   "uniform mediump sampler%s samp;\n"                                           \
+   "in vec4 tc;\n"                                                       \
+   "void main() {\n"                                                     \
+   "   gl_FragDepth = float(texelFetch(samp, %s(tc%s), int(tc.z)).x);\n" \
+   "}\n"
+
+
 #define FS_TEXFETCH_DS_MSAA_GL HEADER_GL FS_TEXFETCH_DS_MSAA_BODY
-#define FS_TEXFETCH_DS_MSAA_GLES HEADER_GLES FS_TEXFETCH_DS_MSAA_BODY
+#define FS_TEXFETCH_DS_MSAA_GLES HEADER_GLES FS_TEXFETCH_DS_MSAA_BODY_GLES
 
 
 #endif