[XEN PATCH] tools: Fix build with recent QEMU, use "--enable-trace-backends"

[Anthony PERARD <anthony.perard@xxxxxxxxxx>]

The configure option "--enable-trace-backend" isn't accepted anymore
and we should use "--enable-trace-backends" instead which was
introduce in 2014 and allow multiple backends.

"--enable-trace-backends" was introduced by:
    5b808275f3bb ("trace: Multi-backend tracing")
The backward compatible option "--enable-trace-backend" is removed by
    10229ec3b0ff ("configure: remove backwards-compatibility and obsolete 
options")

As we already use ./configure options that wouldn't be accepted by
older version of QEMU's configure, we will simply use the new spelling
for the option and avoid trying to detect which spelling to use.

We already make use if "--firmwarepath=" which was introduced by
    3d5eecab4a5a ("Add --firmwarepath to configure")
which already include the new spelling for "--enable-trace-backends".

Signed-off-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>
---
 tools/Makefile | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/Makefile b/tools/Makefile
index 9e28027835..4906fdbc23 100644
--- a/tools/Makefile
+++ b/tools/Makefile
@@ -218,9 +218,9 @@ subdir-all-qemu-xen-dir: qemu-xen-dir-find
        mkdir -p qemu-xen-build; \
        cd qemu-xen-build; \
        if $$source/scripts/tracetool.py --check-backend --backend log ; then \
-               enable_trace_backend='--enable-trace-backend=log'; \
+               enable_trace_backend="--enable-trace-backends=log"; \
        elif $$source/scripts/tracetool.py --check-backend --backend stderr ; 
then \
-               enable_trace_backend='--enable-trace-backend=stderr'; \
+               enable_trace_backend='--enable-trace-backends=stderr'; \
        else \
                enable_trace_backend='' ; \
        fi ; \
-- 
Anthony PERARD