scripts: correctly warn when the local tarballs directory does not exist

Warn about a missing local tarball directory, only if it was configured.
Avoid the spurious message:
Directory '${CT_LOCAL_TARBALLS_DIR}' does not exist.
Will not save downloaded tarballs to local storage.

Thanks to "Pedro I. Sanchez" <psanchez@colcan.ca> for pointing out the
issue:
http://sourceware.org/ml/crossgcc/2009-12/msg00011.html

configure: install in a sub-dir of --libdir and --docdir

In case the user specifies the LIBDIR with --libdir , or DOCDIR with
--docdir, install our support files in a sub-dir, so as not to mangle
existing (potentially system) files/dirs.
(transplanted from 991fc21dd3cfda7d6448388b3224821f6937f15e)

configure: install in a sub-dir of --libdir and --docdir

In case the user specifies the LIBDIR with --libdir , or DOCDIR with
--docdir, install our support files in a sub-dir, so as not to mangle
existing (potentially system) files/dirs.

scripts: directly spit-out the date in the WiKi table, misc eye-candy

No need to go through a post-processing just for displaying the date...

scripts: fix Host/Target colums in WiKi table

Generate a better-looking WiKi table by re-arranging
the host and target columns.

scripts: fix WiKi table generation

The number of column in the top-most header was not updated to reflect the
fact that a new column was added to show the host (for canadian crosses).

samples: update the Alpha sample

According to: http://sourceware.org/ml/crossgcc/2009-11/msg00109.html

libc/glibc: update 2.10.1 patchset

According to: http://sourceware.org/ml/crossgcc/2009-11/msg00109.html
update the patchset for correct Alpha build.

patches/glibc: allows glibc2.9 to be compiled with binutils 2.20

the configure script had to be modified to accept as/ld at versions greater
than 2.19
Signed-off-by: Frederic Roussel <fr.frasc@gmail.com>

samples: update the AVR32 sample