cheets: Add external/wayland and external/cheets-libffi

wayland-client will be used by the hardware composer.
libffi is required by libwayland-client.

BUG=b/25324609
TEST=drm_hwcomposer.cpp compiles/links when including "wayland-client.h"
     and calling wl_display_connect(NULL)

Change-Id: I2d05e174b5044b11fae798d93ef2fd1090b70f1f
diff --git a/testsuite/libffi.call/complex_longdouble.c b/testsuite/libffi.call/complex_longdouble.c
new file mode 100644
index 0000000..7e78366
--- /dev/null
+++ b/testsuite/libffi.call/complex_longdouble.c
@@ -0,0 +1,10 @@
+/* Area:	ffi_call
+   Purpose:	Check complex types.
+   Limitations:	none.
+   PR:		none.
+   Originator:	<vogt@linux.vnet.ibm.com>.  */
+
+/* { dg-do run } */
+
+#include "complex_defs_longdouble.inc"
+#include "complex.inc"