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.
diff --git a/ssl/ssl_cert.c b/ssl/ssl_cert.c
index 7f4739d..605e97e 100644
--- a/ssl/ssl_cert.c
+++ b/ssl/ssl_cert.c
@@ -106,7 +106,7 @@
 
 #include <stdio.h>
 
-#include "openssl/e_os.h"
+#include "e_os.h"
 #ifndef NO_SYS_TYPES_H
 # include <sys/types.h>
 #endif