Optimizing: Improve const-string code generation.

For strings in the boot image, use either direct pointers
or pc-relative addresses. For other strings, use PC-relative
access to the dex cache arrays for AOT and direct address of
the string's dex cache slot for JIT.

For aosp_flounder-userdebug:
  - 32-bit boot.oat: -692KiB (-0.9%)
  - 64-bit boot.oat: -948KiB (-1.1%)
  - 32-bit dalvik cache total: -900KiB (-0.9%)
  - 64-bit dalvik cache total: -3672KiB (-1.5%)
    (contains more files than the 32-bit dalvik cache)
For aosp_flounder-userdebug forced to compile PIC:
  - 32-bit boot.oat: -380KiB (-0.5%)
  - 64-bit boot.oat: -928KiB (-1.0%)
  - 32-bit dalvik cache total: -468KiB (-0.4%)
  - 64-bit dalvik cache total: -1928KiB (-0.8%)
    (contains more files than the 32-bit dalvik cache)

Bug: 26884697
Change-Id: Iec7266ce67e6fedc107be78fab2e742a8dab2696
diff --git a/compiler/linker/relative_patcher.cc b/compiler/linker/relative_patcher.cc
index 6727c17..3a22983 100644
--- a/compiler/linker/relative_patcher.cc
+++ b/compiler/linker/relative_patcher.cc
@@ -62,10 +62,10 @@
       LOG(FATAL) << "Unexpected relative call patch.";
     }
 
-    virtual void PatchDexCacheReference(std::vector<uint8_t>* code ATTRIBUTE_UNUSED,
-                                        const LinkerPatch& patch ATTRIBUTE_UNUSED,
-                                        uint32_t patch_offset ATTRIBUTE_UNUSED,
-                                        uint32_t target_offset ATTRIBUTE_UNUSED) {
+    void PatchPcRelativeReference(std::vector<uint8_t>* code ATTRIBUTE_UNUSED,
+                                  const LinkerPatch& patch ATTRIBUTE_UNUSED,
+                                  uint32_t patch_offset ATTRIBUTE_UNUSED,
+                                  uint32_t target_offset ATTRIBUTE_UNUSED) OVERRIDE {
       LOG(FATAL) << "Unexpected relative dex cache array patch.";
     }