check-non-portable-shell.pl: wc -l may have leading WS

Test scripts count number of lines in an output and check it againt
its expectation.  fb3340a ("test-lib: introduce test_line_count to
measure files", 2010-10-31) introduced a helper to show a failure in
such a test in a more readable way than comparing `wc -l` output with
a number.

Besides, on some platforms, "$(wc -l <file)" is padded with leading
whitespace on the left, so

	test "$(wc -l <file)" = 4

would not work (most notably on macosX); the users of test_line_count
helper would not suffer from such a portability glitch.

Add a check in check-non-portable-shell.pl to find '"' between
`wc -l` and '=' and hint the user about test_line_count().

Signed-off-by: Torsten Bögershausen <[email protected]>
Reviewed-by: Johannes Schindelin <[email protected]>
Helped-by: Eric Sunshine <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: tboegi

t/check-non-portable-shell.pl

@@ -21,6 +21,7 @@ sub err {
 	/^\s*declare\s+/ and err 'arrays/declare not portable';
 	/^\s*[^#]\s*which\s/ and err 'which is not portable (please use type)';
 	/\btest\s+[^=]*==/ and err '"test a == b" is not portable (please use =)';
+	/\bwc -l.*"\s*=/ and err '`"$(wc -l)"` is not portable (please use test_line_count)';
 	/\bexport\s+[A-Za-z0-9_]*=/ and err '"export FOO=bar" is not portable (please use FOO=bar && export FOO)';
 	# this resets our $. for each file
 	close ARGV if eof;