toolchain:
 * bump gcc-4.6.x version to 4.6.4 (self-built toolchain only)
 * download-toolchain is still 4.6.3 even if menuconfig says 4.6.4 (will also be updated to 4.6.4 within the next couple of days)
 * refs #1939


git-svn-id: file:///var/svn/freetz/trunk@10380 149334a1-2f27-0410-a3b9-fc62619ac1e6