cleanup src/linux and src/misc trees, etc.

previously, it was pretty much random which one of these trees a given
function appeared in. they have now been organized into:

src/linux: non-POSIX linux syscalls (possibly shard with other nixen)
src/legacy: various obsolete/legacy functions, mostly wrappers
src/misc: still mostly uncategorized; some misc POSIX, some nonstd
src/crypt: crypt hash functions

further cleanup will be done later.

src/crypt/crypt.c

@@ -0,0 +1,11 @@
+#include <unistd.h>
+#include <crypt.h>
+
+char *__crypt_r(const char *, const char *, struct crypt_data *);
+
+char *crypt(const char *key, const char *salt)
+{
+	/* Note: update this size when we add more hash types */
+	static char buf[128];
+	return __crypt_r(key, salt, (struct crypt_data *)buf);
+}