nettle: fix ptest failure

nettle: fix ptest failure

Rework dlopen-test.patch to fix below
dlopen-test failure:
 # cd /usr/lib64/nettle/ptest
 # ./run-ptest
 dlopen failed: /usr/lib/libnettle.so: cannot open shared object file: No such file or directory
 ./run-ptest: line 8:  7607 Aborted                 "./$f"
 FAIL: dlopen-test

As the test dlopen-test depends on libnettle.so
which belongs to nettle-dev package, so add it
to rdepends of nettle-ptest.

(From OE-Core rev: 524fcf34128045f9f5726a1f1b8715a12b12ae7c)

Signed-off-by: Mingli Yu <Mingli.Yu@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>