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>

Index: ltrace-0.5.3/configure

===================================================================

--- ltrace-0.5.3/configure

+++ ltrace-0.5.3/configure

@@ -78,7 +78,10 @@ fi

 rm -f conftest.c a.out

 CFLAGS='-g -O2'

-LIBS='-lelf -lsupc++ -liberty '

+LIBS='-lelf'

+[ -n "$HAVE_LIBSUPC__" ] && LIBS="$LIBS -lsupc++"

+[ -n "$HAVE_LIBIBERTY" ] && LIBS="$LIBS -liberty"

+

 INSTALL='install -c'

 iquote='-iquote '

 iquoteend=''