Do not load .eh_frame section from separete object files

Do not load .eh_frame section from separete object files

We don't need to read the .eh_frame section from the separate
object files, because this data is already present in the
main executable (it needs to, or the program wouldn't work).

We discovered this investigating a problem with the 'next' command,
which was due to unwind failures, which came from the fact that
the .eh_frame was incorrectly relocated.

gdb/ChangeLog (Tristan Gingold):

    * dwarf2-frame.c (dwarf2_build_frame_info): Do not load .eh_frame
    section in separate object files.