misc/iscan-proprietary-drivers: Fixed to detect ARCH.

Failed to build on x86_64 because of hardcoded 'i586'. There is an x86_64
download listed in .info, so fixed by detecting ARCH properly.

Signed-off-by: Willy Sudiarto Raharjo <willysr@slackbuilds.org>

misc/iscan-proprietary-drivers/iscan-proprietary-drivers.SlackBuild

@@ -24,10 +24,17 @@
 
 PRGNAM=iscan-proprietary-drivers
 VERSION=2.10.0.1
-ARCH=${ARCH:-i586}
 BUILD=${BUILD:-1}
 TAG=${TAG:-_SBo}
 
+if [ -z "$ARCH" ]; then
+  case "$( uname -m )" in
+    i?86) ARCH=i586 ;;
+    arm*) ARCH=arm ;;
+       *) ARCH=$( uname -m ) ;;
+  esac
+fi
+
 CWD=$(pwd)
 TMP=${TMP:-/tmp/SBo}
 PKG=$TMP/package-$PRGNAM