creating workflow for mirror::String compression

All-ASCII String characters are stored in 8-bit blocks
instead of 16-bit. The compression has not taken place, but all
workflow are in the code already (changing kUseStringCompression in
string.h file to TRUE will enable the feature)

Notes: Feature works on interpreter only without optimizing

Test art: m ART_TEST_INTERPRETER=true ART_TEST_OPTIMIZING=false
          test-art-host

Also tested with String tests from libcore/:
1. libcore.java.lang.StringTest
2. libcore.java.lang.StringBufferTest
3. libcore.java.lang.StringBuilderTest
4. libcore.java.lang.OldStringTest
5. libcore.java.lang.OldStringBufferTest

Memory improvement is 33% (from 6.03% to 4.03%, total String memory
from all apps per total memory of all apps) measured on Angler
with Hprof tools

Bug: 31040547
Change-Id: I9cc92c265ebf1305fc06b5fc33efd83797660cce
diff --git a/runtime/common_runtime_test.h b/runtime/common_runtime_test.h
index f445e52..2d16a49 100644
--- a/runtime/common_runtime_test.h
+++ b/runtime/common_runtime_test.h
@@ -207,6 +207,12 @@
     return; \
   }
 
+#define TEST_DISABLED_FOR_STRING_COMPRESSION() \
+  if (mirror::kUseStringCompression) { \
+    printf("WARNING: TEST DISABLED FOR STRING COMPRESSION\n"); \
+    return; \
+  }
+
 }  // namespace art
 
 namespace std {