libchromeos: remove Linux host build restriction

Now that minijail and libchrome are built on non-Linux, this isn't
needed.

BUG=24073089
TEST=mm on a mac

Change-Id: I247ac9c0ba38d86919312fe8a0c563fd520c45fb
diff --git a/Android.mk b/Android.mk
index a68f68e..04734ad 100644
--- a/Android.mk
+++ b/Android.mk
@@ -14,8 +14,6 @@
 
 LOCAL_PATH := $(call my-dir)
 
-ifeq ($(HOST_OS),linux)
-
 libchromeos_cpp_extension := .cc
 libchromeos_core_sources := \
     chromeos/asynchronous_signal_handler.cc \
@@ -313,5 +311,3 @@
 runtargettests: libchromeos_test
 	adb sync
 	adb shell su shell /data/nativetest/libchromeos_test/libchromeos_test
-
-endif # HOST_OS == linux