qemu-build: Disable -Werror

Werror is useful for the qemu developers, but not for us. When building
for CI we want a binary to be produced if at all possible.

Change-Id: Ife36a3d97100ed64c280acee766887c8c5d68dd8
Signed-off-by: Joel Stanley <joel@jms.id.au>
diff --git a/qemu-build.sh b/qemu-build.sh
index 6404576..7a5b533 100755
--- a/qemu-build.sh
+++ b/qemu-build.sh
@@ -116,6 +116,7 @@
     --disable-gnutls \
     --disable-vte \
     --disable-vnc \
+    --disable-werror \
     --disable-vnc-png
 make -j4