Include e_os.h from ec_lcl.h

The EC code recently started using REF_PRINT_COUNT and REF_ASSERT_ISNT.
Those are defined in e_os.h.
Reviewed-by: NRich Salz <rsalz@openssl.org>

crypto/ec/ec_lcl.h

@@ -74,6 +74,8 @@
 #include <openssl/ec.h>
 #include <openssl/bn.h>
 
+#include "e_os.h"
+
 #if defined(__SUNPRO_C)
 # if __SUNPRO_C >= 0x520
 #  pragma error_messages (off,E_ARRAY_OF_INCOMPLETE_NONAME,E_ARRAY_OF_INCOMPLETE)