scripts/functions: do not abort on failed extract

For glibc/eglibc, if the add-on can not be extracted, we want to catch
the error to print a meaningful error message.

So:
- try to extract the tarball
- if it fails, print a waring instead of calling CT_Abort
- return 1

So, components that want to catch the error and want to handle it can,
while components that do not will gracefuly fail thanks to our catching
every errors.

Bonus: it works without changing any existing extract procedure! :-)

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>

 # Bare metal config options

 ## select BARE_METAL

 ##

 ## help 'Bare metal' refers to those programs that run without any kernel.

 ## help

 ## help You probably want to say 'y' here if you plan to use your compiler

 ## help to build bootloaders. It is not yet suitable to build Linux kernels,

 ## help though, because the APCI stuff relies on the target C library headers

 ## help being available?!?!...