build: set RDMA related _LIBS and _CFLAGS only if building with RDMA support

Having to force {ibverbs,rdmacm}_{LIBS,CFLAGS} looks positively odd;
so this may warrant further review. However, they are definitely not
needed if building without RDMA support.

Signed-off-by: Florian Haas <florian.haas@linbit.com>
Reviewed-by: Steven Dake <sdake@redhat.com>
(cherry picked from commit e715a455b6fc2582f505f4b24ac1500068687ba9)

corosync.spec.in

@@ -57,10 +57,12 @@ BuildRoot: %(mktemp -ud %{_tmppath}/%{name}-%{version}-%{release}-XXXXXX)
 ./autogen.sh
 %endif
 
+%if %{with rdma}
 export ibverbs_CFLAGS=-I/usr/include/infiniband \
 export ibverbs_LIBS=-libverbs \
 export rdmacm_CFLAGS=-I/usr/include/rdma \
 export rdmacm_LIBS=-lrdmacm \
+%endif
 %{configure} \
 	--enable-nss \
 %if %{with testagents}