Move prebuilt library dependencies of bionic-unit-tests to Blueprint

Test: atest CtsBionicTestCases
Test: m bionic-unit-tests && adb sync data && \
  adb shell /data/nativetest[64]/bionic-unit-tests/bionic-unit-tests
Change-Id: I94b1eacfe496375853a476bd6c6702d09cfdbcce
diff --git a/tests/gtest_globals.cpp b/tests/gtest_globals.cpp
index 4160237..5b5ede8 100644
--- a/tests/gtest_globals.cpp
+++ b/tests/gtest_globals.cpp
@@ -24,8 +24,9 @@
 #include <string>
 
 std::string GetTestlibRoot() {
-  // Calculate ANDROID_DATA assuming the binary is in "$ANDROID_DATA/somedir/binary-dir/binary"
-  std::string path = android::base::Dirname(android::base::GetExecutablePath()) + "/..";
+  // Typically the executable is /data/nativetest[64]/bionic-unit-tests/bionic-unit-tests, and the
+  // test libraries are in /data/nativetest[64]/bionic-loader-test-libs.
+  std::string path = android::base::GetExecutableDirectory() + "/..";
 
   std::string out_path;
   if (!android::base::Realpath(path.c_str(), &out_path)) {