librsvg2: multiple unspecified vulnerabilities

Update to 2.40.7. This contains various security fixes for which CVEs have apparently not yet been issued.

From the Mageia bug report:

Version 2.40.7

• - Bugs fixed from fuzz testing: #703102, #738050, #738169, #744270, #744299
• - Fixed unfiled bug from fuzz testing, where the convolution filter had an integer multiplication overflow.
• - Fix build of rsvg-convert on Windows.
• - Fix a bunch of compiler warnings.