e_os.h does not belong with the exported headers. Do not put it there

and make all files the depend on it include it without prefixing it
with openssl/.

This means that all Makefiles will have $(TOP) as one of the include
directories.

ssl/ssl_task.c

@@ -124,7 +124,7 @@ int LIB$INIT_TIMER(), LIB$SHOW_TIMER();
 #include <string.h>		/* from ssltest.c */
 #include <errno.h>
 
-#include "openssl/e_os.h"
+#include "e_os.h"
 
 #include <openssl/buffer.h>
 #include <openssl/x509.h>