e_os.h removal from other headers and source files.

Removed e_os.h from all bar three headers (apps/apps.h crypto/bio/bio_lcl.h and
ssl/ssl_locl.h).

Added e_os.h into the files that need it now.

Directly reference internal/nelem.h when required.

Reviewed-by: Andy Polyakov <appro@openssl.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4188)

ssl/s3_lib.c

diff --git a/ssl/s3_lib.c b/ssl/s3_lib.c
index fdccdb7..1a5c3f7 100644
--- a/ssl/s3_lib.c
+++ b/ssl/s3_lib.c
@@ -11,7 +11,9 @@
 
 #include <stdio.h>
 #include <openssl/objects.h>
+#include "internal/nelem.h"
 #include "ssl_locl.h"
+#include "e_os.h"
 #include <openssl/md5.h>
 #include <openssl/dh.h>
 #include <openssl/rand.h>