objtool: Disable GCC '-Wpacked' warnings

Objtool is failing to build with GCC 4.4.7 due to the following
warnings:

  cc1: warnings being treated as errors
  In file included from orc.h:21,
                   from orc_gen.c:21:
  orc_types.h:86: error: packed attribute is unnecessary for ‘sp_offset’
  orc_types.h:87: error: packed attribute is unnecessary for ‘bp_offset’
  orc_types.h:88: error: packed attribute is unnecessary for ‘sp_reg’

I suspect those warnings are a GCC bug.  But -Wpacked isn't very useful
anyway, so just disable it.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 627fce14 ("objtool: Add ORC unwind table generation")
Link: http://lkml.kernel.org/r/76d85d7b5a87566465095c500bce222ff5d7b146.1501188854.git.jpoimboe@redhat.comSigned-off-by: Ingo Molnar <mingo@kernel.org>

tools/objtool/Makefile

@@ -25,7 +25,8 @@ OBJTOOL_IN := $(OBJTOOL)-in.o
 all: $(OBJTOOL)
 
 INCLUDES := -I$(srctree)/tools/include -I$(srctree)/tools/arch/$(HOSTARCH)/include/uapi
-CFLAGS   += -Wall -Werror $(EXTRA_WARNINGS) -Wno-switch-default -Wno-switch-enum -fomit-frame-pointer -O2 -g $(INCLUDES)
+WARNINGS := $(EXTRA_WARNINGS) -Wno-switch-default -Wno-switch-enum -Wno-packed
+CFLAGS   += -Wall -Werror $(WARNINGS) -fomit-frame-pointer -O2 -g $(INCLUDES)
 LDFLAGS  += -lelf $(LIBSUBCMD)
 
 # Allow old libelf to be used: