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

This reverts commit a3a49fe863e0bcf423ed0b4082136d1439fb2e79.

Change-Id: I0afabec15f5d9110de0d4105cbab7d040f2b86e2
diff --git a/compiler/driver/compiler_driver.cc b/compiler/driver/compiler_driver.cc
index 7cb7489..47288b5 100644
--- a/compiler/driver/compiler_driver.cc
+++ b/compiler/driver/compiler_driver.cc
@@ -74,8 +74,8 @@
 
 static constexpr bool kTimeCompileMethod = !kIsDebugBuild;
 
-// Whether to produce 64-bit ELF files for 64-bit targets.
-static constexpr bool kProduce64BitELFFiles = true;
+// Whether to produce 64-bit ELF files for 64-bit targets. Leave this off for now.
+static constexpr bool kProduce64BitELFFiles = false;
 
 // Whether classes-to-compile and methods-to-compile are only applied to the boot image, or, when
 // given, too all compilations.