Remove recursive ALWAYS_INLINE

GCC (mips32 Buildbot) is complaining about recursive inlining.

Clean up after
    https://android-review.googlesource.com/#/c/214918/.

Change-Id: I221c53c32403e5e433e30cfee7b2ae36680f39e6
diff --git a/runtime/gc/space/image_space.cc b/runtime/gc/space/image_space.cc
index 7a2b8d7..d386c74 100644
--- a/runtime/gc/space/image_space.cc
+++ b/runtime/gc/space/image_space.cc
@@ -812,7 +812,7 @@
         ForwardObject(obj));
   }
 
-  ALWAYS_INLINE void operator()(mirror::Object* obj) const NO_THREAD_SAFETY_ANALYSIS {
+  void operator()(mirror::Object* obj) const NO_THREAD_SAFETY_ANALYSIS {
     if (visited_->Test(obj)) {
       // Already visited.
       return;