uclibc: Use gcc-cross-initial as staging compiler

uclibc: Use gcc-cross-initial as staging compiler

Do not build fake shared libraries during uclibc-initial phase

Let uclibc depend on gcc-cross-initial instead of gcc-cross-intermediate
thereby set stage to remove gcc-cross-intermediate

Let uclibc depend on uclibc-initial so that boostrap sysroot
gets populated properly

Signed-off-by: Khem Raj <raj.khem@gmail.com>