The problem was solved a long time ago, through some hit on google. I cant find it now, but it was something about the NDK directory, i had to move or copy some files in the structure. It might have been something like this
As far as I remember it was something similar to this (answer posted by Andy on openfl):
Copy the files from ${ANDROID_NDK_ROOT}\sources\cxx-stl\gnu-libstdc++\4.4.3\ to ${ANDROID_NDK_ROOT}\sources\cxx-stl\gnu-libstdc++\
Here's the link to his answer, and some similar questions above:
http://www.openfl.org/developer/forums/installing-openfl/beginner-questions-android-build-failed/