girepository/build: Actually use our compiler to generate GLib typelibs

We are overriding the default g-ir-compiler for local usage, but this
is not actually happen since that's computed while parsing introspection

So generate the compiler as first thing, then in case handle the
introspection data

girepository/meson.build

@@ -240,6 +240,8 @@ pkg.generate(libgirepository,
   libraries: [libglib_dep, libgobject_dep],
 )
 
+subdir('compiler')
+
 if enable_gir
   subdir('introspection')
 endif
@@ -248,6 +250,5 @@ if build_tests
   subdir('tests')
 endif
 
-subdir('compiler')
 subdir('decompiler')
-subdir('inspector')
+subdir('inspector')