Fix glibc dependency to gcc-intermediate

In commit ebc81933, we reverted 2babed4a, but meanwhile eglibc/ was
renamed glibc/ so rules eglibc-build must be renamed glibc-build to
correctly work.

Signed-off-by: Jérôme Pouiller <jezz@sysmic.org>
Acked-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>