x86: Deprecate a.out support

Linux supports ELF binaries for ~25 years now.  a.out coredumping has
bitrotten quite significantly and would need some fixing to get it into
shape again but considering how even the toolchains cannot create a.out
executables in its default configuration, let's deprecate a.out support
and remove it a couple of releases later, instead.

Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Richard Weinberger <richard@nod.at>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Jann Horn <jannh@google.com>
Cc: <linux-api@vger.kernel.org>
Cc: <linux-fsdevel@vger.kernel.org>
Cc: lkml <linux-kernel@vger.kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: <x86@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/x86/Kconfig

@@ -14,7 +14,6 @@ config X86_32
 	select ARCH_WANT_IPC_PARSE_VERSION
 	select CLKSRC_I8253
 	select CLONE_BACKWARDS
-	select HAVE_AOUT
 	select HAVE_GENERIC_DMA_COHERENT
 	select MODULES_USE_ELF_REL
 	select OLD_SIGACTION
@@ -2843,6 +2842,7 @@ config IA32_EMULATION
 config IA32_AOUT
 	tristate "IA32 a.out support"
 	depends on IA32_EMULATION
+	depends on BROKEN
 	---help---
 	  Support old a.out binaries in the 32bit emulation.
 

arch/x86/um/Kconfig

@@ -16,7 +16,6 @@ config 64BIT
 
 config X86_32
 	def_bool !64BIT
-	select HAVE_AOUT
 	select ARCH_WANT_IPC_PARSE_VERSION
 	select MODULES_USE_ELF_REL
 	select CLONE_BACKWARDS