[librsvg] (22 commits) ...rsvg-test.c: Don't leak the cwd

[Federico Mena Quintero <federico src gnome org>]

Summary of changes:

  0ccc1d8... wip: try to port drawing_ctx to rust (*)
  b054df6... bbox: remove the C export (*)
  603b29f... drawing_ctx: pass the context to the draw callback (*)
  3156161... Clone the draw_ctx's bbox so the ctx doesn't get borrowed (*)
  10f5167... Compute effects region in a way to not cause a double mutab (*)
  ffc59ce... Store RsvgNode in draw_ctx.acquired_nodes, not pointers to  (*)
  8b37a31... Use a RefCell for the vector of acquired nodes (*)
  6287274... Clone a bbox to avoid causing a borrow (*)
  ffabcab... DrawCtx is always mutable in the filter context (*)
  90b3682... DrawingCtx.get_cr_stack() doesn't need a mutable ctx (*)
  1fe8599... Don't keep a &DrawingCtx in FilterContext; pass it around t (*)
  3e99ac5... link.rs: Remove the with_tag() convenience function; use th (*)
  1e101c7... add_node_and_ancestors_to_stack(): Fix mutability (*)
  8b464fb... impl Drop for AcquiredNode: Fix mutability (*)
  b982ccc... draw_node_from_stack(): Don't use an anonymous function hel (*)
  347c83a... Merge branch 'master' into drawing-ctx-wip (*)
  d35aa27... rsvg_drawing_ctx_new() - fix the type of the cr argument (*)
  a9ebc8c... drawing_ctx.rs: Restore the original behavior of the cr_sta
  b4283ff... is_cairo_context_nested(): Oops, the condition was backward
  dca2e4f... draw_node_from_stack(): Ahem, make this work in the origina
  2cccd10... sax_processing_instruction_cb(): Don't leak the pbag iterat
  2a03a22... rsvg-test.c: Don't leak the cwd

(*) This commit already existed in another branch; no separate mail sent