t: move "git add submodule" into test blocks

Some submodule tests do some setup outside of a test_expect
block. This is bad because we won't actually check the
outcome of those commands. But it's doubly so because "git
add submodule" now produces a warning to stderr, which is
not suppressed by the test scripts in non-verbose mode.

This patch does the minimal to fix the annoying warnings.
All three of these scripts could use more cleanup of related
setup.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: peff

t/t4041-diff-submodule-option.sh

@@ -430,9 +430,11 @@ test_expect_success 'deleted submodule' '
 	test_cmp expected actual
 '
 
-test_create_repo sm2 &&
-head7=$(add_file sm2 foo8 foo9) &&
-git add sm2
+test_expect_success 'create second submodule' '
+	test_create_repo sm2 &&
+	head7=$(add_file sm2 foo8 foo9) &&
+	git add sm2
+'
 
 test_expect_success 'multiple submodules' '
 	git diff-index -p --submodule=log HEAD >actual &&

t/t4060-diff-submodule-option-diff-format.sh

@@ -643,9 +643,11 @@ test_expect_success 'deleted submodule' '
 	test_cmp expected actual
 '
 
-test_create_repo sm2 &&
-head7=$(add_file sm2 foo8 foo9) &&
-git add sm2
+test_expect_success 'create second submodule' '
+	test_create_repo sm2 &&
+	head7=$(add_file sm2 foo8 foo9) &&
+	git add sm2
+'
 
 test_expect_success 'multiple submodules' '
 	git diff-index -p --submodule=diff HEAD >actual &&

t/t7401-submodule-summary.sh

@@ -241,9 +241,11 @@ EOF
 	test_cmp expected actual
 "
 
-test_create_repo sm2 &&
-head7=$(add_file sm2 foo8 foo9) &&
-git add sm2
+test_expect_success 'create second submodule' '
+	test_create_repo sm2 &&
+	head7=$(add_file sm2 foo8 foo9) &&
+	git add sm2
+'
 
 test_expect_success 'multiple submodules' "
 	git submodule summary >actual &&