Correct testing for compat task. Always use our own test.

Correct testing for compat task. Always use our own test.

is_compat_task(), when defined in the kernel, is really just for testing
whether or not we are in a 32-compat syscall. It does not definitely tell
us whether or not the current task is a 32bit compat task. So always use
our own test_thread_flag() with the arch specific TIF_flag.

* runtime/autoconf-is-compat-task.c: Removed.
* buildrun.cxx (compile_pass): Remove is-compat-task check.
* runtime/compatdefs.h: Detect s390 specific TIF flag. Always define
  _stp_is_compat_task() when CONFIG_COMPAT defined.
* tapset/conversions.stp (user_long): Use _stp_is_compat_task().
  (user_long_warn): Likewise.