ICU-21081 Make U_ASSERT C++14 compatible

Author: sffc

icu4c/source/common/uassert.h

@@ -32,7 +32,7 @@
 # include <assert.h>
 # define U_ASSERT(exp) assert(exp)
 #elif U_CPLUSPLUS_VERSION
-# define U_ASSERT(exp) void()
+# define U_ASSERT(exp) (void)0
 #else
 # define U_ASSERT(exp)
 #endif