[XEN PATCH 2/2] automation: Check if ninja is available before building QEMU

[Anthony PERARD <anthony.perard@xxxxxxxxxx>]

ninja is now required to build the latest version of QEMU, some
container still don't have ninja and attempting to add it breaks the
build for different reasons, so QEMU will be skip on those containers.

Failures:
- ubuntu/xenial:
    fatal: ninja version (1.5.1) incompatible with build file 
ninja_required_version version (1.7.1).
- debian/unstable-i386: (debian-unstable-32)
    /build/tools/flask/policy/Makefile.common:115: *** target pattern contains 
no '%'.  Stop.
- suse/opensuse-tumbleweed:
    failed to build iPXE
- debian/unstable:
    update of the container fails with:
        The following packages have unmet dependencies:
         clang-8 : Depends: libstdc++-8-dev but it is not installable
                   Depends: libgcc-8-dev but it is not installable
                   Depends: libobjc-8-dev but it is not installable
                   Recommends: llvm-8-dev but it is not going to be installed
                   Recommends: libomp-8-dev but it is not going to be installed

Signed-off-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>
---
 automation/scripts/build | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/automation/scripts/build b/automation/scripts/build
index 46b6903d2922..d8c77e244cda 100755
--- a/automation/scripts/build
+++ b/automation/scripts/build
@@ -46,7 +46,9 @@ if ! test -z "$(ldd /bin/ls|grep musl|head -1)"; then
 fi
 
 # Qemu requires Python 3.5 or later
-if ! type python3 || python3 -c "import sys; res = sys.version_info < (3, 5); 
exit(not(res))"; then
+# QEMU requires ninja
+if ! type python3 || python3 -c "import sys; res = sys.version_info < (3, 5); 
exit(not(res))" \
+        || ! type ninja; then
     cfgargs+=("--with-system-qemu=/bin/false")
 fi
 
-- 
Anthony PERARD