Make eglibc's extra_config an array containing ./configure options

Change extra_config from a string to a array of options.

configure: check for bash-3.1 or above

This is required to use the array variables that came with bash-3.1.

[libc-eglibc] Rewrite part of the code

Rewrite part of the code to better match the rest.
Most notably, rewrite handling of:
if [ ... ] && [ ... ]
to:
if [ ... -a ... ]

This has the positive side effect of calling "[" only once, although
"[" is probably a shell built-in.

[libc-eglibc] Fix testing for existing files

To test for existing files, use "[ -f blabla ]", not "[ -a blabla ]"
Checking for a file exsitence with "-a" is a bashism.
Althoug we _are_ using bash, it's disturbing as it can be misread as
the 'and' operator. Fix by using "-f".

samples: add eglibc-based toolchain for MIPS.

config: add Linux kernel 2.6.30.5

config: update Linux kernel long-term stable to 2.6.27.31.

Merge the AVR32 support branch to the default branch.

Removed debug line

Fix libc config