I'm hitting an issue where some test infrastructure is setting
LD_LIBRARY_PATH to a list that contains both 32-bit and 64-bit
libraries because it is unsure whether the code under test is going to
execute 32-bit or 64-bit processes or both.  When using musl the
dynamic loader takes the first library with a matching name and then
fails to load it if it is for the wrong elf class.

The attached patch verifies the elf machine and class when searching
the path list, continuing the search if a valid elf header with an
incorrect machine or class is found.