Require ninja for ppconsul (#1294)

Fixes compilation problem on CentOS7

defaults-alo.sh

@@ -36,6 +36,10 @@ overrides:
       set -e
       which gfortran || { echo "gfortran missing"; exit 1; }
       which cc && test -f $(dirname $(which cc))/c++ && printf "#define GCCVER ((__GNUC__ << 16)+(__GNUC_MINOR__ << 8)+(__GNUC_PATCHLEVEL__))\n#if (GCCVER < 0x070300)\n#error \"System's GCC cannot be used: we need at least GCC 7.X. We are going to compile our own version.\"\n#endif\n" | cc -xc++ - -c -o /dev/null
+  Ppconsul:
+    build_requires:
+      - CMake
+      - ninja
   ROOT:
     tag: "v6-14-04"
     source: https://github.com/root-mirror/root