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.h b/tests/gtest_globals.h
index b3c7b10..1bebb70 100644
--- a/tests/gtest_globals.h
+++ b/tests/gtest_globals.h
@@ -19,8 +19,10 @@
 
 #include <string>
 
-constexpr const char* kPrebuiltElfDir = "prebuilt-elf-files";
-
 std::string GetTestlibRoot();
 
+inline std::string GetPrebuiltElfDir() {
+  return GetTestlibRoot() + "/prebuilt-elf-files";
+}
+
 #endif  // _BIONIC_TESTS_GTEST_GLOBALS_H