base: Mirax/Mirax2.2-4-PNG.zip
# libpng 1.5 says "unknown critical chunk", 1.6 says "unhandled"
error: "^PNG error: IHDZ: un.+ critical chunk$"
slide: Mirax2.2-4-PNG.mrxs
success: false
vendor: mirax
regions:
- [50000, 100000, 9, 100, 100]

base: Mirax/Mirax2.2-4-PNG.zip
# libpng 1.5 says "unknown critical chunk", 1.6 says "unhandled",
# 1.6.13 says "CRC error"
error: "^PNG error: IHDZ: (un.+ critical chunk|CRC error)$"
slide: Mirax2.2-4-PNG.mrxs
success: false
vendor: mirax
regions:
- [50000, 100000, 9, 100, 100]

Add another error string for mirax-png-bad-image
test: Add another error string for mirax-png-bad-image
