Revert "Use homogeneous space compaction if proper flag is set."

This reverts commit 44bd8c1cc4d8e0ffcdbdf51ed496af94fc2083e5.

Change-Id: Ie62307d5b5bd0135d871855c5c5182add1c40939
diff --git a/runtime/Android.mk b/runtime/Android.mk
index 1cdb236..61bc9ff 100644
--- a/runtime/Android.mk
+++ b/runtime/Android.mk
@@ -328,10 +328,6 @@
   LIBART_CFLAGS += -DUSE_JEMALLOC
 endif
 
-ifeq ($(ART_USE_HSPACE_COMPACT),true)
-  LIBART_CFLAGS += -DART_USE_HSPACE_COMPACT
-endif
-
 # $(1): target or host
 # $(2): ndebug or debug
 define build-libart
diff --git a/runtime/parsed_options.cc b/runtime/parsed_options.cc
index 7836d32..7e2283d 100644
--- a/runtime/parsed_options.cc
+++ b/runtime/parsed_options.cc
@@ -80,14 +80,7 @@
     gc::kCollectorTypeCMS),
 #error "ART default GC type must be set"
 #endif
-    background_collector_type_(
-#ifdef ART_USE_BACKGROUND_COMPACT
-        gc::kCollectorTypeSS),
-#elif defined(ART_USE_HSPACE_COMPACT)
-        gc::kCollectorTypeHomogeneousSpaceCompact),
-#else
-    gc::kCollectorTypeNone),
-#endif
+    background_collector_type_(gc::kCollectorTypeHomogeneousSpaceCompact),
                                                     // If background_collector_type_ is
                                                     // kCollectorTypeNone, it defaults to the
                                                     // collector_type_ after parsing options. If