nettle-ptest: fix a failing test

This patch changes the result of the nettle dlopen-test
from FAIL to PASS. The test used to fail because the test could not
find and load libnettle.so.
This patch fixes this by using absolute path instead of relative.

This was the only test out of 88 that used to fail.

(From OE-Core rev: f12d493418417c8529a97c7a768e4af58ea5c91b)

Signed-off-by: Juro Bystricky <juro.bystricky@intel.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-support/nettle/nettle-3.3/dlopen-test.patch

@@ -0,0 +1,20 @@
+Replace relative path of libnettle.so with absolute path so the test
+program can find it.
+Relative paths are not suitable, as the folder strucure for ptest
+is different from the one expected by the nettle testsuite.
+
+Upstream-Status: Inappropriate [embedded specific]
+
+Signed-off-by: Juro Bystricky <juro.bystricky@intel.com>
+
+--- a/testsuite/dlopen-test.c	2016-10-01 00:28:38.000000000 -0700
++++ b/testsuite/dlopen-test.c	2017-10-13 11:08:57.227572860 -0700
+@@ -9,7 +9,7 @@
+ main (int argc UNUSED, char **argv UNUSED)
+ {
+ #if HAVE_LIBDL
+-  void *handle = dlopen ("../libnettle.so", RTLD_NOW);
++  void *handle = dlopen ("/usr/lib/libnettle.so", RTLD_NOW);
+   int (*get_version)(void);
+   if (!handle)
+     {

meta/recipes-support/nettle/nettle_3.3.bb

@@ -11,5 +11,9 @@ SRC_URI += "\
             file://check-header-files-of-openssl-only-if-enable_.patch \
             "
 
+SRC_URI_append_class-target = "\
+            file://dlopen-test.patch \
+            "
+
 SRC_URI[md5sum] = "10f969f78a463704ae73529978148dbe"
 SRC_URI[sha256sum] = "46942627d5d0ca11720fec18d81fc38f7ef837ea4197c1f630e71ce0d470b11e"