PR17073: module probes: support out-of-tree modules

PR17073: module probes: support out-of-tree modules

This patch adds support for out-of-tree modules by specifying the
fullpath. This did not work before because both the _stp_module struct
and the stap_dwarf_probe struct were using the full path as the module
name. This caused issues during relocation of module sections/kprobe
addresses.

In this patch, we use the already existing modname_from_path() function
to modify the module member of the dwarf_derived_probe (which later
affects the stap_dwarf_probe struct) and to emit the proper name in
dump_unwindsym_cxt() for the _stp_module struct.