ldconfig: filter out non-existing directories from default path

[kib]

Summary

This is done only for ld-elf32.so.1, where /lib32 is kept in the path
due to the way STANDARD_LIBRARY_PATH is defined in rtld_paths.h.

This change fixes innocent warning appearing after
99132daf6f70cb0cc969c555d3612547fa3cf1db

[emaste]

libexec/rc/rc.d/ldconfig

56–61

or avoid the extra variable,

for x in $(/libexec/ld-elf32.so.1 -v | sed -n -e '/^Default lib path /s///p' | tr : ' '); do
...
done

[kib]

Remove _LOC1

[dim]

This looks fine to me.