strace: upgrade to 4.8, supporting now aarch64, and xtensa

Remove 'strace-fix-arm-bad-syscall.patch'. This patch had been integrated
in v4.6 (commit: 9bc6340d2) and was later replaced with a generic solution
in v.7 (commit: 2ce12ed31c2).

Strace still cannot handle non-LFS environments, so a modified version of
strace-fix-disabled-largefile-syscalls.patch remains. The 64-bit syscalls
(sys_truncate64, etc.) are references in the sysent structure but the
functinon definitions are commented out becuase of the missing LFS support.

The workaround for the 'forced lfs mode' doesn't seem to be necessary anymore.

Build tested on arm w and w/o LFS support.

[Peter: arc still not supported]
Signed-off-by: Chris Zankel <chris@zankel.net>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>