Merge remote-tracking branch 'public/tags/tracing-pull-request' into …

…staging

# gpg: Signature made Tue 29 Nov 2016 10:07:16 AM GMT
# gpg:                using RSA key 0x9CA4ABB381AB73C8
# gpg: Good signature from "Stefan Hajnoczi <stefanha@redhat.com>"
# gpg:                 aka "Stefan Hajnoczi <stefanha@gmail.com>"
# Primary key fingerprint: 8695 A8BF D3F9 7CDA AC35  775A 9CA4 ABB3 81AB 73C8

* public/tags/tracing-pull-request:
  configure: fix LTTng UST tracing backend detection

Message-id: 20161129100724.15207-1-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

configure

@@ -4305,11 +4305,11 @@ if have_backend "ust"; then
 #include <lttng/tracepoint.h>
 int main(void) { return 0; }
 EOF
-  if compile_prog "" "" ; then
+  if compile_prog "" "-Wl,--no-as-needed -ldl" ; then
     if $pkg_config lttng-ust --exists; then
       lttng_ust_libs=$($pkg_config --libs lttng-ust)
     else
-      lttng_ust_libs="-llttng-ust"
+      lttng_ust_libs="-llttng-ust -ldl"
     fi
     if $pkg_config liburcu-bp --exists; then
       urcu_bp_libs=$($pkg_config --libs liburcu-bp)