Make copy_required_libs() more robust

On some systems ldd gives a slightly different output for VDSOs. It doesn't
contain a '=>'. E.g.:
   linux-vdso.so.1 (0x00007fff2f4a6000)
instead of:
   linux-vdso.so.1 => (0x00007fff2f4a6000)
This patch simply skips all entries in the ldd output which don't expand to a
path name to workaround that.

Change-Id: Ie37637890b775b36bb31af4e586e61131bd80fa8
Merge "Make copy_required_libs() more robust"