Convert art runtests to Android.bp

Build the art runtest libraries with Android.bp.  The host test
libraries move from out/host/linux-x86/lib[64] to
out/host/linux-x86/nativetest[64], and the device test libraires from
/data/artest/${TARGET_ARCH} to /data/nativetest[64]/art/${TARGET_ARCH},
which requires adding nativetest to the library search path, and fixing
some tests to support multiple entries in library search paths.

Test: m -j test-art-host
Test: m -j test-art-target
Change-Id: I2118a3292f22f275954ddd7cdd4e12287fe47808
diff --git a/cmdline/Android.bp b/cmdline/Android.bp
index c9cd9dc..c811cbd 100644
--- a/cmdline/Android.bp
+++ b/cmdline/Android.bp
@@ -17,7 +17,7 @@
 art_cc_test {
     name: "art_cmdline_tests",
     defaults: [
-        "art_test_defaults",
+        "art_gtest_defaults",
     ],
     srcs: ["cmdline_parser_test.cc"],
 }