parse-options: remove unused OPT_SET_PTR

OPT_SET_PTR was never used since its creation at db7244bd
(parse-options new features., 2007-11-07).

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

t/t0040-parse-options.sh

@@ -30,7 +30,6 @@ String options
     --string2 <str>       get another string
     --st <st>             get another string (pervert ordering)
     -o <str>              get another string
-    --default-string      set string to default
     --list <str>          add str to list
 
 Magic arguments
@@ -293,7 +292,7 @@ cat > expect <<EOF
 boolean: 0
 integer: 0
 timestamp: 1
-string: default
+string: (not set)
 abbrev: 7
 verbose: 0
 quiet: yes
@@ -302,8 +301,8 @@ file: (not set)
 arg 00: foo
 EOF
 
-test_expect_success 'OPT_DATE() and OPT_SET_PTR() work' '
-	test-parse-options -t "1970-01-01 00:00:01 +0000" --default-string \
+test_expect_success 'OPT_DATE() works' '
+	test-parse-options -t "1970-01-01 00:00:01 +0000" \
 		foo -q > output 2> output.err &&
 	test_must_be_empty output.err &&
 	test_cmp expect output