testing/tests/download: test git submodules

Add two submodules as static repos, add a branch to the main static repo
and check on the git refs test case the download of a git package:
 - repo with submodule but without support in the package;
 - repo with recursive submodules with support in the package.

Signed-off-by: Ricardo Martincoski <ricardo.martincoski@datacom.ind.br>
Cc: Arnout Vandecappelle <arnout@mind.be>
[Arnout: remove handling of inconsistent tarball hashes - that's an
 actual bug that should be fixed]
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>

support/testing/tests/download/git-remote/refs-sub1.git/.gitattributes

@@ -0,0 +1 @@
+objects/*/* binary

support/testing/tests/download/git-remote/refs-sub1.git/HEAD

@@ -0,0 +1 @@
+cb545facf77bbc5f24f95b6d503c338d10b7b717

support/testing/tests/download/git-remote/refs-sub1.git/config

@@ -0,0 +1,4 @@
+[core]
+	repositoryformatversion = 0
+	filemode = true
+	bare = true

support/testing/tests/download/git-remote/refs-sub1.git/objects/cb/545facf77bbc5f24f95b6d503c338d10b7b717

@@ -0,0 +1 @@
+x
­Î˝
Â0@ajOq$:;˛#„X€&8˙…q,S°=‘(číW<=_rćjśv­ĆÖ&‡(˝“:Y§U"e“1a<31>0B#<23>•#9AĎv+.쩆gŞŤW_w†Cý`źżxš3ńŇű’Ź 5N¨Ť4*D±é6Ńâźr‚WnL‹Wž×ş’Rç^ű_fĹW`

support/testing/tests/download/git-remote/refs-sub1.git/refs/heads/submodule

@@ -0,0 +1 @@
+1df823cb8a6d1866148ae50a8009762a9c4c777f