Revert "Revert "Switch to using ELF-64 for 64-bit architectures.""

This reverts commit 650f0c49ac4aff3c9f871cd041042ae28b7e1e0a.

Bug: 21403573
Change-Id: I9e46b08ffa75dd7ed8641c8ba610d23d08ddd3ef
diff --git a/compiler/driver/compiler_driver.cc b/compiler/driver/compiler_driver.cc
index f988812..4945a91 100644
--- a/compiler/driver/compiler_driver.cc
+++ b/compiler/driver/compiler_driver.cc
@@ -75,8 +75,8 @@
 
 static constexpr bool kTimeCompileMethod = !kIsDebugBuild;
 
-// Whether to produce 64-bit ELF files for 64-bit targets. Leave this off for now.
-static constexpr bool kProduce64BitELFFiles = false;
+// Whether to produce 64-bit ELF files for 64-bit targets.
+static constexpr bool kProduce64BitELFFiles = true;
 
 // Whether classes-to-compile and methods-to-compile are only applied to the boot image, or, when
 // given, too all compilations.