ARM: VIXL32: Pass initial ART tests with new code generator.

- Implement enough codegen to pass ~70 art/tests.

- When ART_USE_VIXL_ARM_BACKEND is defined:
  - Blacklist known-to-fail target tests
  - interpret-only everything except the tests themselves
  - Set a flag to use the VIXL based ARM backend

Test: export ART_USE_VIXL_ARM_BACKEND=true && mma test-art-target && mma test-art-host

Change-Id: Ic8bc095e8449f10f97fa0511284790f36c20e276
diff --git a/build/art.go b/build/art.go
index 1164cbc..ccaa11d 100644
--- a/build/art.go
+++ b/build/art.go
@@ -74,6 +74,12 @@
 		cflags = append(cflags, "-fstack-protector")
 	}
 
+	if envTrue(ctx, "ART_USE_VIXL_ARM_BACKEND") {
+		// Used to enable the new VIXL-based ARM code generator.
+		cflags = append(cflags, "-DART_USE_VIXL_ARM_BACKEND=1")
+		asflags = append(asflags, "-DART_USE_VIXL_ARM_BACKEND=1")
+	}
+
 	return cflags, asflags
 }