intel: call intel_check_front_buffer_rendering() in intelClear()

fixes bug 24953.

src/mesa/drivers/dri/intel/intel_clear.c

@@ -33,6 +33,7 @@
 
 #include "intel_context.h"
 #include "intel_blit.h"
+#include "intel_buffers.h"
 #include "intel_chipset.h"
 #include "intel_clear.h"
 #include "intel_fbo.h"
@@ -75,6 +76,8 @@ intelClear(GLcontext *ctx, GLbitfield mask)
    struct gl_framebuffer *fb = ctx->DrawBuffer;
    GLuint i;
 
+   intel_check_front_buffer_rendering(intel);
+
    if (0)
       fprintf(stderr, "%s\n", __FUNCTION__);