master f1f0608fd1: Don't use XRender to fill rectangles unless an alpha channel exists

[Po Lu]

branch: master
commit f1f0608fd1316b4f9a0fde99293e0c9ee5ef7ea3
Author: Po Lu <luangruo@yahoo.com>
Commit: Po Lu <luangruo@yahoo.com>

    Don't use XRender to fill rectangles unless an alpha channel exists
    
    * src/xterm.c (x_clear_area): Don't use XRender unless
    `alpha_bits' is set.
---
 src/xterm.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/xterm.c b/src/xterm.c
index 843483b594..68488b3ef5 100644
--- a/src/xterm.c
+++ b/src/xterm.c
@@ -4769,7 +4769,8 @@ x_clear_area (struct frame *f, int x, int y, int width, 
int height)
 #if defined HAVE_XRENDER && \
   (RENDER_MAJOR > 0 || (RENDER_MINOR >= 2))
       x_xr_ensure_picture (f);
-      if (FRAME_X_PICTURE (f) != None
+      if (FRAME_DISPLAY_INFO (f)->alpha_bits
+         && FRAME_X_PICTURE (f) != None
          && FRAME_CHECK_XR_VERSION (f, 0, 2))
        {
          XRenderColor xc;