Log Message:
librsvg: update to 2.40.19.

Version 2.40.19
- bgo#621088: Using text objects as clipping paths is now supported.
- bgo#587721: Fix rendering of text elements with transformations (Massimo).
- bgo#777833 - Fix memory leaks when an RsvgHandle is disposed before
  being closed (Philip Withnall).
- bgo#782098 - Don't pass deprecated options to gtk-doc (Ting-Wei Lan).
- bgo#786372 - Fix the default for the "type" attribute of the \ 
<style> element.
- bgo#785276 - Don't crash on single-byte files.
- bgo#634514: Don't render unknown elements and their sub-elements.
- bgo#777155 - Ignore patterns that have close-to-zero dimensions.
- bgo#634324 - Fix Gaussian blurs with negative scaling.
- Fix the <switch> element; it wasn't working at all.
- Fix loading when rsvg_handle_write() is called one byte at a time.
- bgo#787895 - Fix incorrect usage of libxml2.  Thanks to Nick Wellnhofer
  for advice on this.
- Backported the test suite machinery from the master branch (Chun-wei Fan,
  Federico Mena).
- We now require Pango 1.38.0 or later (released in 2015).
- We now require libxml2 2.9.0 or later (released in 2012).