x86/compat: Make mmap_is_ia32() common compat

TIF_ADDR32 is set for both ia32 and x32 tasks, so change from
CONFIG_IA32_EMULATION to CONFIG_COMPAT.  Use config_enabled()
to make the function more readable.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1434974121-32575-3-git-send-email-brgerst@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/include/asm/elf.h

@@ -344,14 +344,9 @@ extern int compat_arch_setup_additional_pages(struct linux_binprm *bprm,
  */
 static inline int mmap_is_ia32(void)
 {
-#ifdef CONFIG_X86_32
-	return 1;
-#endif
-#ifdef CONFIG_IA32_EMULATION
-	if (test_thread_flag(TIF_ADDR32))
-		return 1;
-#endif
-	return 0;
+	return config_enabled(CONFIG_X86_32) ||
+	       (config_enabled(CONFIG_COMPAT) &&
+		test_thread_flag(TIF_ADDR32));
 }
 
 /* Do not change the values. See get_align_mask() */