Remove useless uses of cat, and replace with filename arguments

Replace uses of cat that do nothing but writing the contents of
a single file to another command via pipe.

[jc: Original patch from Josh was somewhat buggy and rewrote
"cat $file | wc -l" to "wc -l $file", but this one should be Ok.]

Signed-off-by: Junio C Hamano <gitster@pobox.com>

git-quiltimport.sh

@@ -70,10 +70,11 @@ tmp_info="$tmp_dir/info"
 commit=$(git rev-parse HEAD)
 
 mkdir $tmp_dir || exit 2
-for patch_name in $(cat "$QUILT_PATCHES/series" | grep -v '^#'); do
+for patch_name in $(grep -v '^#' < "$QUILT_PATCHES/series" ); do
 	echo $patch_name
-	(cat $QUILT_PATCHES/$patch_name | git mailinfo "$tmp_msg" "$tmp_patch" > "$tmp_info") || exit 3
-	test -s .dotest/patch || {
+	git mailinfo "$tmp_msg" "$tmp_patch" \
+		<"$QUILT_PATCHES/$patch_name" >"$tmp_info" || exit 3
+	test -s "$tmp_patch" || {
 		echo "Patch is empty.  Was it split wrong?"
 		exit 1
 	}