scripts: fix binutils-version.sh for 'as' without a package.

Commit 73c25753 fixed the common issue that binutil packages (tool/organization
that packaged or built the bin-utils) are included in brackets and this may
falsely be recognized as a version.  However, some tools do not provide a
'package' and previously we add the 'Gnu assembler..' to the version.

Strip out the '(package version text)' and then look for a ##.## string.

Signed-off-by: Bill Pringlemeir <bpringlemeir@nbsps.com>
Tested-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Tested-by: Hans de Goede <hdegoede@redhat.com>