Do not stop if ARCHIVE_FILENAME is corrupt

Apparently VF785_20140321.tar.xz is corrupt and the following error
is returned when extracting the archive:

    ...
    VF785/external/webkit/Source/WebCore/html/PluginDocument.h
    VF785/external/webkit/Source/WebCore/CMakeListsWinCE.txt
    VF785/external/webkit/Source/WebCore/ChangeLog-2005-12-19
    xz: (stdin): Unexpected end of input
    tar: Unexpected EOF in archive
    tar: Unexpected EOF in archive
    tar: Error is not recoverable: exiting now

Appending "|| true" to prevent the script to break.

Signed-off-by: Gianpaolo Macario <gmacario@gmail.com>