tools: Work around BITS_PER_LONG related build failure in objtool

The objtool build fails with the recent changes to the bits-per-long
headers:

  tools/include/linux/bitops.h:12:0: error: "BITS_PER_LONG" redefined [-Werror]

Which got introduced by:

  bb9707077b4e tools: Copy the bitsperlong.h files from the kernel

Work it around for the time being.

Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

tools/include/linux/bitops.h

@@ -9,7 +9,9 @@
 #define __WORDSIZE (__SIZEOF_LONG__ * 8)
 #endif
 
-#define BITS_PER_LONG __WORDSIZE
+#ifndef BITS_PER_LONG
+# define BITS_PER_LONG __WORDSIZE
+#endif
 
 #define BIT_MASK(nr)		(1UL << ((nr) % BITS_PER_LONG))
 #define BIT_WORD(nr)		((nr) / BITS_PER_LONG)