libc/eglibc: fix downloading

Since Subversion 1.6.13 was released, it is no longer possible
to checkout/export to the current working directory using '.'
(eg. "svn co bla://blabla/foo/bar ." no longer extracts the content
of bar into ./ but into ./bar).

Fix this by luring Subversion to extract into "$(pwd)", which has
the advantage of working both with all known versions so far.

At the same time, remove the useless redirection.
(transplanted from 42cc9bd0db7ea6d690efab40742881414f7c1277)

# Compute Alpha-specific values

CT_DoArchTupleValues () {

    # The architecture part of the tuple:

    CT_TARGET_ARCH="${CT_ARCH}${CT_ARCH_ALPHA_VARIANT}"

}