configure: add the missing help output for optional features

Signed-off-by: NLin Ma <lma@suse.com>
Message-Id: <20170310101405.26974-1-lma@suse.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

configure

@@ -1330,6 +1330,12 @@ Advanced options (experts only):
   --with-vss-sdk=SDK-path  enable Windows VSS support in QEMU Guest Agent
   --with-win-sdk=SDK-path  path to Windows Platform SDK (to build VSS .tlb)
   --tls-priority           default TLS protocol/cipher priority string
+  --enable-gprof           QEMU profiling with gprof
+  --enable-profiler        profiler support
+  --enable-xen-pv-domain-build
+                           xen pv domain builder
+  --enable-debug-stack-usage
+                           track the maximum stack usage of stacks created by qemu_alloc_stack
 
 Optional features, enabled with --enable-FEATURE and
 disabled with --disable-FEATURE, default is enabled if available:
@@ -1397,6 +1403,12 @@ disabled with --disable-FEATURE, default is enabled if available:
   tcmalloc        tcmalloc support
   jemalloc        jemalloc support
   replication     replication support
+  vhost-vsock     virtio sockets device support
+  opengl          opengl support
+  virglrenderer   virgl rendering support
+  xfsctl          xfsctl support
+  qom-cast-debug  cast debugging support
+  tools           build qemu-io, qemu-nbd and qemu-image tools
 
 NOTE: The object files are built at the place where configure is launched
 EOF