Remove MOJO_DISALLOW_COPY_AND_ASSIGN and MOJO_ALLOW_UNUSED_LOCAL.

mojo/public/c/system/macros.h

Index: mojo/public/c/system/macros.h
diff --git a/mojo/public/c/system/macros.h b/mojo/public/c/system/macros.h
index 7f28e1836623c2749944ad9fa8ef4131611de29d..26f5982ec14cbbfb2583d8806837a70e87504a89 100644
--- a/mojo/public/c/system/macros.h
+++ b/mojo/public/c/system/macros.h
@@ -7,12 +7,6 @@
 
 #include <stddef.h>
 
-// Annotate a variable indicating it's okay if it's unused.
-// Use like:
-//   int x = ...;
-//   MOJO_ALLOW_UNUSED_LOCAL(x);
-#define MOJO_ALLOW_UNUSED_LOCAL(x) false ? (void)x : (void)0
-
 // Annotate a function indicating that the caller must examine the return value.
 // Use like:
 //   int foo() MOJO_WARN_UNUSED_RESULT;