Fix Ninja build failure by escaping $(MAKE) in Yosys build command

Author: soheilshahrouz

libs/EXTERNAL/CMakeLists.txt

@@ -47,7 +47,7 @@ if (${WITH_PARMYS})
 	SET(YOSYS_BUILD_DIR ${CMAKE_BINARY_DIR}/bin/yosys)
 
     add_definitions("-D_YOSYS_")
-    set(MAKE_PROGRAM "$(MAKE)")
+    set(MAKE_PROGRAM "$$MAKE")
 	set(CURRENT_CPPFLAGS "$(CPPFLAGS)-w")
 	if(${CMAKE_GENERATOR} STREQUAL "Ninja")
 	    set(CURRENT_CPPFLAGS "-w")