This is needed to be able to run check-links.sh against a "sysrooted"
binary while ensuring that the ldd(1) call done on the host uses the
host libc. It is not possible to set LD_LIBRARY_PATH before calling
check-links.sh as then the "sysrooted" libc would be incorrectly used.
A LD_PRELOAD=libc.so is used to ldd(1) as it needs to use the host libc
to run. ldd(1) is a simple wrapper around execve(2) and dlopen(2) with
env LD_TRACE_LOADED_OBJECTS set. Due to the dlopen(2) restriction on
shared library tracing ldd(1) is still required for this lookup.
Sponsored by: EMC / Isilon Storage Division
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