Add support for ANDROID_RUNTIME_ROOT variable

This commit introduces the ANDROID_RUNTIME_ROOT environment
variable in preparation for its use within the runtime module.

As a module, ART must no longer use the Android-wide
ANDROID_ROOT environment variable as the base of default
paths for module content. ANDROID_RUNTIME_ROOT will take over
the responsibility. It remains a variable to unify host
and device treatment.

Some test methods (SetUpAndroidData, TearDownAndroidData
SetUpAndroidRoot) have been renamed to clarify their purpose.

Bug: 119935277
Test: build / treehugger
Change-Id: I7c7de52911cbfa56cef90270425ed369176c4767
diff --git a/compiler/utils/assembler_test_base.h b/compiler/utils/assembler_test_base.h
index 778a015..5fa0b3c 100644
--- a/compiler/utils/assembler_test_base.h
+++ b/compiler/utils/assembler_test_base.h
@@ -59,12 +59,12 @@
       disassembler_cmd_name_(disasm),
       disassembler_parameters_(disasm_params) {
     // Fake a runtime test for ScratchFile
-    CommonRuntimeTest::SetUpAndroidData(android_data_);
+    CommonRuntimeTest::SetUpAndroidDataDir(android_data_);
   }
 
   virtual ~AssemblerTestInfrastructure() {
     // We leave temporaries in case this failed so we can debug issues.
-    CommonRuntimeTest::TearDownAndroidData(android_data_, false);
+    CommonRuntimeTest::TearDownAndroidDataDir(android_data_, false);
     tmpnam_ = "";
   }