fault-injection: allow stacktrace filter for x86-64

This patchset allow fault injection to run on x86_64 and makes stacktrace
filter work as expected.  With this, we can test a device driver module
with fault injection more easily.


This patch (of 4):

FAULT_INJECTION_STACKTRACE_FILTER option was apparently disallowed on
x86_64 because of problems with the stack unwinder:

    commit 6d690dc
    Author: Akinobu Mita <[email protected]>
    Date:   Sat May 12 10:36:53 2007 -0700

        fault injection: disable stacktrace filter for x86-64

However, there is no problems whatsoever with this today. Let's allow
it again.

Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Wei Yongjun <[email protected]>
Cc: Akinobu Mita <[email protected]>
Cc: Nathan Chancellor <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Nick Desaulniers <[email protected]>
Cc: Josh Poimboeuf <[email protected]>
Cc: Dan Williams <[email protected]>
Cc: Miguel Ojeda <[email protected]>
Cc: Isabella Basso <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Rasmus Villemoes <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: Wei Yongjun

lib/Kconfig.debug

@@ -1982,7 +1982,6 @@ config FAIL_SUNRPC
 config FAULT_INJECTION_STACKTRACE_FILTER
 	bool "stacktrace filter for fault-injection capabilities"
 	depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
-	depends on !X86_64
 	select STACKTRACE
 	depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86
 	help