Fixes #3661.

There are a couple of cases in which ldd won't operate on an executable,
for example when the executable is statically linked.

This patch makes the call to ldd to ldd more resilient against errors,
and looks for the system libc, instead of the libc go-ipfs was linked against.

License: MIT
Signed-off-by: Lars Gierth <larsg@systemli.org>