Windows,examples: //examples/shell now works

The targets in //examples/shell:* now use the Bash
runfiles library in
@bazel_tools//tools/bash/runfiles and work on
Windows.

Also undef the RUNFILES_* envvars in
bazel_example_test::test_shell (which builds the
shell example project) so that the runfiles
library discovers its own runfiles instead of
trying (and failing) to use the enclosing test's
runfiles (which it shouldn't use, because the test
executes "bazel run //examples/shell:bin" so that
target's runfiles are independent of the enclosing
test's runfiles).

Fixes https://github.com/bazelbuild/bazel/issues/3839

Closes #5480.

Change-Id: I44f9bf9b11f7fac0e1c0995a44c2336846dc2bc8
PiperOrigin-RevId: 202313105

examples/shell/BUILD

diff --git a/examples/shell/BUILD b/examples/shell/BUILD
index 4b51df1..095cea4 100644
--- a/examples/shell/BUILD
+++ b/examples/shell/BUILD
@@ -3,7 +3,10 @@
 sh_binary(
     name = "bin",
     srcs = ["bin.sh"],
-    deps = [":lib"],
+    deps = [
+        ":lib",
+        "@bazel_tools//tools/bash/runfiles",
+    ],
 )
 
 sh_library(
@@ -12,6 +15,7 @@
         "data/file.txt",
         "lib.sh",
     ],
+    deps = ["@bazel_tools//tools/bash/runfiles"],
 )
 
 sh_test(
@@ -19,7 +23,10 @@
     size = "small",
     srcs = ["test.sh"],
     data = ["data/test_file.txt"],
-    deps = [":lib"],
+    deps = [
+        ":lib",
+        "@bazel_tools//tools/bash/runfiles",
+    ],
 )
 
 filegroup(