Fix .dSYM and .swiftmodule files filtering in find_binary_files()

[krin-san]

search_list.each ... .reject doesn't work at all due to incorrectly written multiline reject block. On my project slather crashes trying to call split on nil and apparently it allowed to pass .dSYM paths to matches_arch function.

I noticed this issue when I built an app using Debug configuration for Generic iOS Device. After that slather crashed trying to lipo nil because .dSYM is a folder and find_binary_file_in_bundle returned nil for it.

Simplified demo on current implementation and two ways to write that right: https://repl.it/repls/BonyConsiderateModel

[coveralls]

Coverage increased (+0.002%) to 95.732% when pulling f0b16e8 on krin-san:bugfix/find_binary_files.reject into aadb417 on SlatherOrg:master.

[ksuther]

Thank you!