x86: fix build error and kconfig for ia32_emulation and binfmt

Fix kconfig warning and build errors on x86_64 by selecting BINFMT_ELF
when COMPAT_BINFMT_ELF is being selected.

warning: (IA32_EMULATION) selects COMPAT_BINFMT_ELF which has unmet direct dependencies (COMPAT && BINFMT_ELF)

fs/built-in.o: In function `elf_core_dump':
compat_binfmt_elf.c:(.text+0x3e093): undefined reference to `elf_core_extra_phdrs'
compat_binfmt_elf.c:(.text+0x3ebcd): undefined reference to `elf_core_extra_data_size'
compat_binfmt_elf.c:(.text+0x3eddd): undefined reference to `elf_core_write_extra_phdrs'
compat_binfmt_elf.c:(.text+0x3f004): undefined reference to `elf_core_write_extra_data'

[ hpa: This was sent to me for -next but it is a low risk build fix ]
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Link: http://lkml.kernel.org/r/51C0B614.5000708@infradead.org
Cc: <stable@vger.kernel.org>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

arch/x86/Kconfig

@@ -2265,6 +2265,7 @@ source "fs/Kconfig.binfmt"
 config IA32_EMULATION
 	bool "IA32 Emulation"
 	depends on X86_64
+	select BINFMT_ELF
 	select COMPAT_BINFMT_ELF
 	select HAVE_UID16
 	---help---