Create BUILD.tools for //tools/test package.

Motivation: as part of fixing issue #5508, I'll
add a cc_binary to this package. The binary will
be embedded in Bazel as a prebuilt binary (to
avoid requiring a C++ compiler to use it).
Therefore //tools/test/BUILD and
@bazel_tools//tools/test/BUILD will contain
different rules, mandating the BUILD file split.

See https://github.com/bazelbuild/bazel/issues/5508

Change-Id: If21bafbc3d83d59e52de498cf3efd2b1b79fa7b6

Closes #5787.

Change-Id: If21bafbc3d83d59e52de498cf3efd2b1b79fa7b6
PiperOrigin-RevId: 208005382
diff --git a/tools/BUILD b/tools/BUILD
index 6192571..c69f44e 100644
--- a/tools/BUILD
+++ b/tools/BUILD
@@ -66,7 +66,7 @@
         "//tools/objc:srcs",
         "//tools/python:embedded_tools",
         "//tools/runfiles:embedded_tools",
-        "//tools/test:srcs",
+        "//tools/test:embedded_tools",
         "//tools/test/LcovMerger/java/com/google/devtools/lcovmerger:embedded_tools",
         "//tools/osx/crosstool:srcs",
         "//tools/osx:srcs",