I have the latest stable debian install, and I wanted to build new kernel. make Xconfig (X means anything) and it reported an error of missing Qt or whatewer, but actually the package pkg-config was missing. I had to look into the sources to find the real reason. So please add pkg-config to the dependencies...
(looks like I do not need the tool pkg-config at all until now, but make Xconfig will fail if pkg-config is not available and will report another kind of error message).