adb seems to build in 64 bit mode these days, so it's safe to build for the simulator too.
While adb is not needed for the simulator, it's handy to have around when you're working with the simulator but need to look at a device.
diff --git a/adb/Android.mk b/adb/Android.mk
index 2296610..c8606cf 100644
--- a/adb/Android.mk
+++ b/adb/Android.mk
@@ -7,7 +7,6 @@
# adb host tool
# =========================================================
-ifneq ($(TARGET_SIMULATOR),true) # not 64 bit clean (also unused with the sim)
include $(CLEAR_VARS)
# Default to a virtual (sockets) usb interface
@@ -77,7 +76,6 @@
$(LOCAL_INSTALLED_MODULE): $(HOST_OUT_EXECUTABLES)/AdbWinApi.dll
endif
-endif
# adbd device daemon
# =========================================================