lib/crypto, efi_loader: avoid multiple inclusions of header files

By adding extra symbols, we can now avoid including x509_parser and
pkcs7_parser.h files multiple times.

Suggested-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Don't include include x509_parser.h twice.
Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
diff --git a/lib/crypto/pkcs7_parser.h b/lib/crypto/pkcs7_parser.h
index 6565fdc..b8234da 100644
--- a/lib/crypto/pkcs7_parser.h
+++ b/lib/crypto/pkcs7_parser.h
@@ -5,6 +5,9 @@
  * Written by David Howells (dhowells@redhat.com)
  */
 
+#ifndef _PKCS7_PARSER_H
+#define _PKCS7_PARSER_H
+
 #include <linux/oid_registry.h>
 #include <crypto/pkcs7.h>
 #include "x509_parser.h"
@@ -63,3 +66,4 @@
 	size_t		data_hdrlen;	/* Length of Data ASN.1 header */
 	const void	*data;		/* Content Data (or 0) */
 };
+#endif /* _PKCS7_PARSER_H */