Fix missing -lpthread in linux-sim build.

It mimics the behavior in libstagefraight/Android.mk
diff --git a/media/libstagefright/omx/Android.mk b/media/libstagefright/omx/Android.mk
index ecd3b2e..46affe7 100644
--- a/media/libstagefright/omx/Android.mk
+++ b/media/libstagefright/omx/Android.mk
@@ -15,11 +15,15 @@
 LOCAL_SHARED_LIBRARIES :=       \
         libbinder               \
         libmedia                \
-	libutils                \
+        libutils                \
         libui                   \
         libcutils               \
         libopencore_common
 
+ifeq ($(TARGET_OS)-$(TARGET_SIMULATOR),linux-true)
+        LOCAL_LDLIBS += -lpthread
+endif
+
 LOCAL_PRELINK_MODULE:= false
 
 LOCAL_MODULE:= libstagefright_omx