ART: Fix 64-bit ELF file support

The API wasn't cross-compile-safe, 32-bit patchoat would fail for
negative delta applied to a 64-bit ELF file.

Add 64-bit ELF file output to the compilers, behind a flag, currently
off by default (preserving current behavior).

Bug: 20095017
Change-Id: I2cde7b4c7cc83413c76692d7b745868d644a604c
diff --git a/runtime/elf_file_impl.h b/runtime/elf_file_impl.h
index a70fa17..16d3857 100644
--- a/runtime/elf_file_impl.h
+++ b/runtime/elf_file_impl.h
@@ -19,6 +19,7 @@
 
 #include <map>
 #include <memory>
+#include <type_traits>
 #include <vector>
 
 // Explicitly include our own elf.h to avoid Linux and other dependencies.
@@ -102,13 +103,13 @@
   // executable is true at run time, false at compile time.
   bool Load(bool executable, std::string* error_msg);
 
-  bool Fixup(uintptr_t base_address);
-  bool FixupDynamic(uintptr_t base_address);
-  bool FixupSectionHeaders(uintptr_t base_address);
-  bool FixupProgramHeaders(uintptr_t base_address);
-  bool FixupSymbols(uintptr_t base_address, bool dynamic);
-  bool FixupRelocations(uintptr_t base_address);
-  bool FixupDebugSections(off_t base_address_delta);
+  bool Fixup(Elf_Addr base_address);
+  bool FixupDynamic(Elf_Addr base_address);
+  bool FixupSectionHeaders(Elf_Addr base_address);
+  bool FixupProgramHeaders(Elf_Addr base_address);
+  bool FixupSymbols(Elf_Addr base_address, bool dynamic);
+  bool FixupRelocations(Elf_Addr base_address);
+  bool FixupDebugSections(typename std::make_signed<Elf_Off>::type base_address_delta);
 
   bool Strip(std::string* error_msg);