ANDROID: kleaf: add kselftest include path

Upstream has moved away from relative path header inclusion for
kselftest.h and ksefltest_harness.h headers. It now uses the compiler
option -I for the non-relative paths. This patch makes the equivalent
change to our bazel file, so that build targets can find the headers.

Cc: Wake Liu <wakel@google.com>
Cc: HONG Yifan <elsk@google.com>
Fixes: e6fbd1759c ("selftests: complete kselftest include centralization")
Change-Id: I77b46c97057f2745feee72ea6a3fced71c1a5544
Signed-off-by: Carlos Llamas <cmllamas@google.com>

BUILD.bazel

@@ -1687,6 +1687,9 @@ cc_library(
     defines = [
         "_GNU_SOURCE=",
     ],
+    includes = [
+        "tools/testing/selftests",
+    ],
     visibility = ["//visibility:private"],
 )