removed useless check

the offset member is an unsigned
fix unused var warning
validate sockets portable way
added comment
remove unused var
partial cleanup to work with size_t str length in password_hash

php_crypt() and co use int, though this is fair enough. Could
be refactored later for tidiness reasons.
separate LDFLAGS and ARFLAGS to fix the unknown opts warns
less spaces in the makefile generated commands