Sourced test snippets: remove shebang and make non-executable

They are installed non-executable, which makes Debian's Lintian
packaging consistency check complain that #! is only useful
in executable scripts. But in fact they are not useful to execute
directly (they rely on setup being done in the script that sources
them), so just chmod them -x.

Closes: #652
Approved by: cgwalters

tests/admin-test.sh

@@ -1,4 +1,5 @@
-#!/bin/bash
+# This file is to be sourced, not executed
+
 # Copyright (C) 2011,2014 Colin Walters <walters@verbum.org>
 #
 # This library is free software; you can redistribute it and/or

tests/archive-test.sh

@@ -1,5 +1,5 @@
-#!/bin/bash
-#
+# This file is to be sourced, not executed
+
 # Copyright (C) 2011 Colin Walters <walters@verbum.org>
 #
 # This library is free software; you can redistribute it and/or

tests/basic-test.sh

@@ -1,5 +1,5 @@
-#!/bin/bash
-#
+# This file is to be sourced, not executed
+
 # Copyright (C) 2011 Colin Walters <walters@verbum.org>
 #
 # This library is free software; you can redistribute it and/or

tests/pull-test.sh

@@ -1,5 +1,5 @@
-#!/bin/bash
-#
+# This file is to be sourced, not executed
+
 # Copyright (C) 2011 Colin Walters <walters@verbum.org>
 #
 # This library is free software; you can redistribute it and/or