Split _stp_module_relocate into kernel and user space lookup functions.

Split _stp_module_relocate into kernel and user space lookup functions.

Simplify relocation logic by splitting kernel and user space module lookups.

* runtime/sym.h (_stp_module_relocate): Split into ...
  (_stp_kmodule_relocate): ... this for kernel module lookups and ...
  (_stp_umodule_relocate): ... this for user space lookups.
* runtime/sym.c: Likewise.
  (_stp_module_check): Use _stp_kmodule_relocate.
* dwflpp.cxx (dwflpp::emit_address): Use _stp_kmodule_relocate or
  _stp_umodule_relocate as appropriate.
* tapsets.cxx (dwarf_derived_probe_group::emit_module_init): Use
  _stp_kmodule_relocate for kprobes.