ecp5: Add ECLKBRIDGECS blackbox

Signed-off-by: David Shah <dave@ds0.me>

techlibs/ecp5/cells_bb.v

diff --git a/techlibs/ecp5/cells_bb.v b/techlibs/ecp5/cells_bb.v
index 0a5046d..ae124e7 100644
--- a/techlibs/ecp5/cells_bb.v
+++ b/techlibs/ecp5/cells_bb.v
@@ -334,6 +334,13 @@
 endmodule
 
 (* blackbox *)
+module ECLKBRIDGECS(
+	input CLK0, CLK1, SEL,
+	output ECSOUT
+);
+endmodule
+
+(* blackbox *)
 module DCCA(
 	input CLKI, CE,
 	output CLKO