In order to be compliant to GPL, all of the source code and build scripts needed to regenerate the patched program from source code, must be distributed (or made available) to the recipient of the binaries of the patched program. The licensee must be able to completely regenerate the patched program based on all the inputs you make available to them under GPL. If they are not able to regenerate the patched program using all your inputs, then you would have not fulfilled the requirements of GPL. (please see the definition of "Corresponding Source" above).
Mod Moved Comments To Chat