Clean up bionic_macros.h a bit.

Use <android-base/macros.h> instead where possible, and move the bionic
macros out of the way of the libbase ones. Yes, there are folks who manage
to end up with both included at once (thanks OpenGL!), and cleaning that
up doesn't seem nearly as practical as just making this change.

Bug: N/A
Test: builds
Change-Id: I23fc544f39d5addf81dc61471771a5438778895b
diff --git a/libc/bionic/scandir.cpp b/libc/bionic/scandir.cpp
index e55be42..0b39049 100644
--- a/libc/bionic/scandir.cpp
+++ b/libc/bionic/scandir.cpp
@@ -90,7 +90,7 @@
     return copy;
   }
 
-  DISALLOW_COPY_AND_ASSIGN(ScandirResult);
+  BIONIC_DISALLOW_COPY_AND_ASSIGN(ScandirResult);
 };
 
 int scandirat(int parent_fd, const char* dir_name, dirent*** name_list,