Small shell fixed to cleanup distfile testing

Fix permissions issue in testenv.sh to clarified chmod on
tools/jdk/BUILD when copying tools into new workspace:
Original script always tried to append but only set it to be writable
after the copy when extra BUILD.* files were available.

Exported is_absolute in test-setup.sh:
rlocation, which is called by tests to properly locate bazel, itself
calls is_absolute. This would generally cause a (presumably recoverable)
error since most tests continue to call a bazel properly.  However,
tests that are inspecting the error log will fail due to the message
error.

Note, that not all tests pass yet. Also getting an issue with:
* scripts/release/testenv.sh : line 38 (file doesn't exist)

* in test_delete_tree_in_unwritable_dir, "fails on first compilation:
due to mkdir: cannot create directory
'bazel-out/local-fastbuild/genfiles/x/unwritable/somedir'

* test_run_under_path 'occasionally' fails to fail
(bazel_test_test.sh:197)

Change-Id: I957a346d320070a310dee4076cc9349ed1e140e1
PiperOrigin-RevId: 152247475

src/test/shell/testenv.sh

@@ -162,6 +162,8 @@ function copy_tools_directory() {
   # tools/jdk/BUILD file for JDK 7 is generated.
   if [ -f tools/jdk/BUILD.* ]; then
     cp tools/jdk/BUILD.* tools/jdk/BUILD
+  fi
+  if [ -f tools/jdk/BUILD ]; then
     chmod +w tools/jdk/BUILD
   fi
   # To support custom langtools

tools/test/test-setup.sh

@@ -114,6 +114,7 @@ else
 fi
 
 export -f rlocation
+export -f is_absolute
 export RUNFILES_MANIFEST_FILE
 
 DIR="$TEST_SRCDIR"