Build the target side of the simulator as 32-bit.

This detail got lost in my previous cleanup change 9b4a812.

Also add a comment explaining why the host side of the
simulator needs to be built in 64-bit (wxWidgets).

Change-Id: I2a867f7f80b43d53e73348b19f6ae834600295f9
diff --git a/core/combo/TARGET_linux-x86.mk b/core/combo/TARGET_linux-x86.mk
index 80adbcf..ddd5c48 100644
--- a/core/combo/TARGET_linux-x86.mk
+++ b/core/combo/TARGET_linux-x86.mk
@@ -22,8 +22,8 @@
 TARGET_CC := $(HOST_CC)
 TARGET_CXX := $(HOST_CXX)
 TARGET_AR := $(HOST_AR)
-TARGET_GLOBAL_CFLAGS := $(HOST_GLOBAL_CFLAGS)
-TARGET_GLOBAL_LDFLAGS := $(HOST_GLOBAL_LDFLAGS)
+TARGET_GLOBAL_CFLAGS := $(HOST_GLOBAL_CFLAGS) -m32
+TARGET_GLOBAL_LDFLAGS := $(HOST_GLOBAL_LDFLAGS) -m32
 TARGET_NO_UNDEFINED_LDFLAGS := $(HOST_NO_UNDEFINED_LDFLAGS)
 else #simulator