Move common CONFIG_UTRACE check to its own function.

Move common CONFIG_UTRACE check to its own function.

* tapsets.cxx (check_process_probe_kernel_support): New function.
  (dwarf_builder::build): Moved CONFIG_UTRACE check to
  check_process_probe_kernel_support() which we call instead.
* tapset-utrace.cxx (utrace_derived_probe::utrace_derived_probe): Call
  check_process_probe_kernel_support() instead of doing CONFIG_UTRACE
  check.
* tapsets.h: Declare check_process_probe_kernel_support().