62c4ec2 Fix potential crash with old XML...

based on: http://github.com/torvalds/subsurface/commit/62c4ec20c7c8395eb2d22011520b6fadc03a87a2

compiled with: mingw 3.4.5

notes:
Signed-off-by: Lubomir I. Ivanov <neolit123@gmail.com>