Skip tests that rely on the `amhello' tarball that comes with Automake.
That tarball's `configure' uses #!/bin/sh, but we can't easily patch it.

diff --git a/t/amhello-binpkg.sh b/t/amhello-binpkg.sh
index fa88cc6..d988cee 100755
--- a/t/amhello-binpkg.sh
+++ b/t/amhello-binpkg.sh
@@ -17,6 +17,7 @@
 # Test an example from the manual about the 'amhello' package:
 # using DESTDIR to build simple, no-frills binary packages.
 
+exit 77
 am_create_testdir=empty
 . ./defs || exit 1
 
diff --git a/t/amhello-cflags.sh b/t/amhello-cflags.sh
index 666011f..2a95e3c 100755
--- a/t/amhello-cflags.sh
+++ b/t/amhello-cflags.sh
@@ -18,6 +18,7 @@
 # using VPATH builds to configure the same package with different
 # options.
 
+exit 77
 am_create_testdir=empty
 required=gcc
 . ./defs || exit 1
diff --git a/t/amhello-cross-compile.sh b/t/amhello-cross-compile.sh
index 708abda..2ee4292 100755
--- a/t/amhello-cross-compile.sh
+++ b/t/amhello-cross-compile.sh
@@ -17,6 +17,7 @@
 # Test an example from the manual about the 'amhello' package:
 # cross-compiling a package from Linux/Unix to MinGW.
 
+exit 77
 am_create_testdir=empty
 required=i586-mingw32msvc-gcc
 . ./defs || exit 1
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<div class='path'>path: <a href='/guix/log/?id=2474b005cd0b7218d790400173a224746295214b'>root</a>/<a href='/guix/log/tests?id=2474b005cd0b7218d790400173a224746295214b'>tests</a>/<a href='/guix/log/tests/challenge.scm?id=2474b005cd0b7218d790400173a224746295214b'>challenge.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/tests/challenge.scm?id=2474b005cd0b7218d790400173a224746295214b&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2021-01-16 11:51:03 +0000'>2021-01-16</span></td><td><a href='/guix/commit/tests/challenge.scm?id=681af17460fa34916ac40589cccdcca7222249af'>guix: Move narinfo code from substitute script to module.</a><span class='msg-avail'>...</span></td><td>Christopher Baines</td></tr>
<tr><td><span title='2020-05-22 01:29:39 +0200'>2020-05-22</span></td><td><a href='/guix/commit/tests/challenge.scm?id=ce0be5675b702b2ff89aed1772ebb42af4150243'>packages: Introduce &lt;content-hash&gt; and use it in &lt;origin&gt;.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2019-12-12 17:56:58 +0100'>2019-12-12</span></td><td><a href='/guix/commit/tests/challenge.scm?id=828a39da68a9169ef1d9f9ff02a1c66b1bcbe884'>challenge: Support "--diff=diffoscope".</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2019-12-12 17:56:58 +0100'>2019-12-12</span></td><td><a href='/guix/commit/tests/challenge.scm?id=5208db3a526e3fcdb8473d9bab8afe498c5f3f76'>challenge: Add "--diff".</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>