There might be some patent issues, and I'm also not quite sure about the license of the source code used.
So instead of ready to use binary, here are some instructions on how to build aac decoder for KolibriOS for yourself!
Prerequisites: Windows environment with Visual studio build tools
and Clang compiler (LLVM)
1. Download attached zip and extract somewhere on your computer
2. Download uaac.h from https://github.com/yui0/slibs/blob/master/uaac.h
and place it in the same folder.
3. Apply uaac.patch
4. Run "compile kolibrios lib.bat" from visual studio prompt (after running VSVARS32.bat) and with Clang compiler installed.
Compiling with Visual Studio might be possible with minor modifications (make the code C11 iso C99 compatible)
To compile with GCC, at least the inline assembly would need to be converted to GCC format.