Add crosstool-ng compile options for GNU variants of grep & make

For building some toolchains with crosstool-ng, newer versions of the GNU variants of make and grep may be required. These changes add the optional requirements out of dupes and pass the path to the GNU executable to crosstool's configure script.
The reason for the option lines was to override the default description. Indeed, crosstool-ng will be compiled with grep and make no matter what, so the default descriptions are not straight forward.