PT_GNU_EH_FRAME segments are contained within PT_LOAD segments, and
so need not be loaded.  Moreover, when we load a segment, we align
it to page boundaries; this overwrites previous contents.  Does
serious damage with small objects (like tst-dir.so) - overwriting
the main function.

Fix by ignoring EH_FRAME segments (libunwind will later re-discover
them when iterating over the objects's phdrs).