riemann-c-client: fix build on bfin

Fixes:
http://autobuild.buildroot.net/results/8de/8de7e533fed3c48fdbe164bc9286148e63494c8f/build-end.log
http://autobuild.buildroot.net/results/828/828a4e09cb14c33b021bd347394104ff8b6dba78/build-end.log
http://autobuild.buildroot.net/results/fc8/fc80326880fb19cd6fbd6c0073916373a52ef873/build-end.log

LD symbol versioning is not working on blackfin even though ld accepts the
--version-script argument, causing link errors, so disable it.

Notice: These autobuilder issues happened with an external fdpic toolchain,
but the issue also occurs with internal toolchain / binutils 2.27 and
fdpic/flat.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/riemann-c-client/riemann-c-client.mk

@@ -15,4 +15,9 @@ RIEMANN_C_CLIENT_DEPENDENCIES = \
 	$(if $(BR2_PACKAGE_GNUTLS),gnutls) \
 	$(if $(BR2_PACKAGE_JSON_C),json-c)
 
+ifeq ($(BR2_bfin),y)
+# ld symbol versioning not working on bfin
+RIEMANN_C_CLIENT_CONF_ENV += ac_cv_prog_ld_version_script=no
+endif
+
 $(eval $(autotools-package))