Fix underquoted m4 entry. This causes a failure if gcrypt isn't present:

| configure: libgcrypt support disabled
| ../rng-tools-5/configure: line 4345: ac_fn_c_try_link: command not found
| configure: error: in `/media/build1/poky/build/tmp/work/i586-poky-linux/rng-tools/5-r0/build':

RP
2016/2/16

Index: rng-tools-5/configure.ac
===================================================================
--- rng-tools-5.orig/configure.ac
+++ rng-tools-5/configure.ac
@@ -71,7 +71,7 @@ AS_IF(
 	[test "x$with_libgcrypt" != "xno"],
 	[
 		AC_CHECK_HEADER([gcrypt.h],
-			AC_CHECK_LIB(
+			[AC_CHECK_LIB(
 				[gcrypt],
 				[gcry_check_version], ,
 				[
@@ -80,7 +80,7 @@ AS_IF(
 						AC_MSG_NOTICE([libgcrypt support disabled])
 					fi
 				]
-			),
+			)],
 			[if test "x$with_libgcrypt" != "xcheck"; then
 				AC_MSG_FAILURE([libgcrypt headers not found]); else
 				AC_MSG_NOTICE([libgcrypt support disabled])