Allow for ninja files to regenerate themselves

scripts/templates/build.ninja.j2

@@ -1,3 +1,4 @@
+ninja_required_version = 1.3
 builddir = {{ buildroot }}
 srcroot = {{ srcroot }}
 
@@ -46,9 +47,24 @@ rule lib
     description = Archiving $name
     command = $ar qcs $out $in
 
+rule regen
+    generator = true
+    description = Regenrating build files
+    command = {{ generator }} ${builddir}
+
 {% for target in targets %}
 subninja {{ target }}/target.ninja
 {% endfor %}
 
+build $
+    {%- for buildfile in buildfiles %}
+    {{ buildfile }} $
+    {%- endfor %}
+    : regen | $
+    {%- for template in templates %}
+    {{ template }} $
+    {%- endfor %}
+    {{ generator }}
+
 # vim: et ts=4 sts=4 sw=4
 

scripts/templates/module.base.ninja.j2

@@ -10,7 +10,7 @@ ccflags = $ccflags $
 {% endblock %}
 
 {% for source in sources %}
-build ${moddir}/{{ source.output }} : {{ source.action }} {{ source.input }}
+build ${moddir}/{{ source.output }} : {{ source.action }} {{ source.input }} || {{ buildfile }}
     name = {{ source.name }}
 {% endfor %}