stat: Nits in stat tests

* Use ourselves as test file instead of /COPYRIGHT, which may or may not
  be present in the test environment.

* atf-check understands \n in strings, use it.

* Some file systems don't like creating small holes, so create large ones
  instead.  This means we need two variables: ps (page size) is the
  minimum size of a data region and the alignment for a hole, while hs
  (hole size) is the minimum size of the holes we create.  This makes no
  difference on FreeBSD but makes it easier to port the test to other
  platforms.

MFC after:	1 week
Sponsored by:	Klara, Inc.
Reviewed by:	kevans
Differential Revision:	https://reviews.freebsd.org/D56304

usr.bin/stat/tests/stat_test.sh

@@ -54,6 +54,7 @@ h_flag_head()
 }
 h_flag_body()
 {
+	file=$(realpath $0)
 	# POSIX defines a hole as “[a] contiguous region of bytes
 	# within a file, all having the value of zero” and requires
 	# that “all seekable files shall have a virtual hole starting
@@ -82,27 +83,27 @@ h_flag_body()
 	atf_check -o inline:"$((ps)) .\n" stat -h .
 	atf_check -o inline:"$((ps)) ." stat -hn .
 
-	# For a file, prints a list of holes.
+	# For a file, prints a list of holes.  Some file systems don't
+	# like creating small holes, so we create large ones instead.
+	hs=$((16*1024*1024))
 	atf_check truncate -s 0 foo
 	atf_check -o inline:"0 foo" \
 	    stat -hn foo
-	atf_check truncate -s "$((ps))" foo
-	atf_check -o inline:"0-$((ps-1)) foo" \
+	atf_check truncate -s "$((hs))" foo
+	atf_check -o inline:"0-$((hs-1)) foo" \
 	    stat -hn foo
-	atf_check dd status=none if=/COPYRIGHT of=foo \
-	    oseek="$((ps))" bs=1 count=1
-	atf_check -o inline:"0-$((ps-1)),$((ps+1)) foo" \
+	atf_check dd status=none if="${file}" of=foo \
+	    oseek="$((hs))" bs=1 count=1
+	atf_check -o inline:"0-$((hs-1)),$((hs+1)) foo" \
 	    stat -hn foo
-	atf_check truncate -s "$((ps*3))" foo
-	atf_check -o inline:"0-$((ps-1)),$((ps*2))-$((ps*3-1)) foo" \
+	atf_check truncate -s "$((hs*3))" foo
+	atf_check -o inline:"0-$((hs-1)),$((hs+ps))-$((hs*3-1)) foo" \
 	    stat -hn foo
 
 	# Test multiple files.
-	atf_check dd status=none if=/COPYRIGHT of=bar
+	atf_check dd status=none if="${file}" of=bar
 	sz=$(stat -f%z bar)
-	atf_check -o inline:"0-$((ps-1)),$((ps*2))-$((ps*3-1)) foo
-$((sz)) bar
-" \
+	atf_check -o inline:"0-$((hs-1)),$((hs+ps))-$((hs*3-1)) foo\n$((sz)) bar\n" \
 	    stat -h foo bar
 
 	# For a device, fail.