Added -lpthread to target LDFLAGS for sim-eng.

This adds "-lpthread" to TARGET_GLOBAL_LDFLAGS when TARGET_SIMULATOR
is true.  This is much easier than inserting it into individual
makefiles as needed.  Has no effect on other builds.

Should fix the sim-eng build breakage in libcameraservice.

Change-Id: I4dcd7d54b93d1be1622b8ce78a1662d28ca9f9f2
diff --git a/core/combo/TARGET_linux-x86.mk b/core/combo/TARGET_linux-x86.mk
index b8f770f..cd7d4b3 100644
--- a/core/combo/TARGET_linux-x86.mk
+++ b/core/combo/TARGET_linux-x86.mk
@@ -23,7 +23,7 @@
 TARGET_CXX := $(HOST_CXX)
 TARGET_AR := $(HOST_AR)
 TARGET_GLOBAL_CFLAGS := $(HOST_GLOBAL_CFLAGS) -m32
-TARGET_GLOBAL_LDFLAGS := $(HOST_GLOBAL_LDFLAGS) -m32
+TARGET_GLOBAL_LDFLAGS := $(HOST_GLOBAL_LDFLAGS) -m32 -lpthread
 TARGET_NO_UNDEFINED_LDFLAGS := $(HOST_NO_UNDEFINED_LDFLAGS)
 TARGET_ARCH_VARIANT := x86
 else #simulator