rng-tools: Fix underquoted m4 and libgcrypt floating dependency

The underquoted m4 caused build failures if libgcrypt wasn't present. The floating
dependency on libgcrypt was just plain incorrect, particularly given the incorrect
libgcrypt RDEPENDS. Change to use PACKAGECONFIG an default to on.

(From OE-Core rev: 17b3044d7508a921916da4979ff8bfbab1e206ce)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-support/rng-tools/rng-tools/underquote.patch

@@ -0,0 +1,31 @@
+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])

meta/recipes-support/rng-tools/rng-tools_5.bb

@@ -5,6 +5,7 @@ LIC_FILES_CHKSUM = "file://COPYING;md5=0b6f033afe6db235e559456585dc8cdc"
 SRC_URI = "http://heanet.dl.sourceforge.net/sourceforge/gkernel/${BP}.tar.gz \
            file://0001-If-the-libc-is-lacking-argp-use-libargp.patch \
            file://0002-Add-argument-to-control-the-libargp-dependency.patch \
+           file://underquote.patch \
            file://init \
            file://default"
 
@@ -20,12 +21,11 @@ python () {
 
 inherit autotools update-rc.d
 
-PACKAGECONFIG = ""
+PACKAGECONFIG = "libgcrypt"
 PACKAGECONFIG_libc-musl = "libargp"
 PACKAGECONFIG_libc-uclibc = "libargp"
 PACKAGECONFIG[libargp] = "--with-libargp,--without-libargp,argp-standalone,"
-
-RDEPENDS_${PN} = "libgcrypt"
+PACKAGECONFIG[libgcrypt] = "--with-libgcrypt,--without-libgcrypt,libgcrypt,"
 
 do_install_append() {
     # Only install the init script when 'sysvinit' is in DISTRO_FEATURES.