Change suspend entrypoint to save all registers.

We avoid the need to save/restore registers in slow paths
and get significant code size savings. On Nexus 9, AOSP:
  - 32-bit boot.oat: -1.4MiB (-1.9%)
  - 64-bit boot.oat: -2.0MiB (-2.3%)
  - other 32-bit oat files in dalvik-cache: -200KiB (-1.7%)
  - other 64-bit oat files in dalvik-cache: -2.3MiB (-2.1%)

Test: Run ART test suite on host and Nexus 9 with gc stress.
Bug: 30212852
Change-Id: I7015afc1e7d30341618c9200a3dc9ae277afd134
diff --git a/compiler/image_writer.cc b/compiler/image_writer.cc
index 063eb11..0f6944a 100644
--- a/compiler/image_writer.cc
+++ b/compiler/image_writer.cc
@@ -1377,6 +1377,8 @@
       runtime->GetCalleeSaveMethod(Runtime::kRefsOnly);
   image_methods_[ImageHeader::kRefsAndArgsSaveMethod] =
       runtime->GetCalleeSaveMethod(Runtime::kRefsAndArgs);
+  image_methods_[ImageHeader::kSaveEverythingMethod] =
+      runtime->GetCalleeSaveMethod(Runtime::kSaveEverything);
   // Visit image methods first to have the main runtime methods in the first image.
   for (auto* m : image_methods_) {
     CHECK(m != nullptr);