[emulator] Produce 64-Bit darwin & linux binaries.

- We now target x64 vs i386 since we no longer support i386.
  This fixes some issues users are seeing around 32-bit binaries.

Change-Id: I7b71107b792b2f04eeebd8cdd2230885931a9578
Bug: b/37132646
Test: file mksdcard => mksdcard: ELF 64-bit LSB  executable, x86-64, version 1 (SYSV)
Test: file mksdcard => mksdcard: Mach-O 64-bit executable x86_64
diff --git a/src/main/groovy/com/android/tools/internal/nativesetup/NativeSetupPlugin.groovy b/src/main/groovy/com/android/tools/internal/nativesetup/NativeSetupPlugin.groovy
index 2c5dd04..0b0ea79 100644
--- a/src/main/groovy/com/android/tools/internal/nativesetup/NativeSetupPlugin.groovy
+++ b/src/main/groovy/com/android/tools/internal/nativesetup/NativeSetupPlugin.groovy
@@ -31,11 +31,11 @@
         project.model {
             platforms {
                 linux {
-                    architecture "i386"
+                    architecture "x86_64"
                     operatingSystem "linux"
                 }
                 darwin {
-                    architecture "i386"
+                    architecture "x86_64"
                     operatingSystem "osx"
                 }
             }