The file "PATCH.libgcc" contains a patch for the GNU compiler "gcc".

There is no need to apply this patch unless (a) you compile djvu using
the cothread threading model, and (b) gcc on your platform implements
exceptions using the sjlj model. The configuration script will test the
presence of the patch and indicate if the patch is necessary.

To use the patch, you must obtain a source code distribution of gcc,
apply the patch to the file "gcc/libgcc2.c", and create a compiler
binary as explained in the gcc documentation.  Then set the environment
variables CC and CXX, and run the djvu configuration script.