Log Message:
vala: update to 0.52.2.

Vala 0.52.2
===========
 * Regression and bug fixes:
  - codegen:
    + Don't free temp-var for element-access to array with boxed structs [#1174]
    + Don't free unowned heap allocated struct

 * Bindings:
  - glib-2.0: Add simple_generics attribute to GenericArray.find_custom()