Add libwinpthread, link it into win32 binaries.

Bug: http://b/31665213
Test: wine adb.exe
Test: wine fastboot.exe
Change-Id: I6d6ff69f0c016e2654119a09161685841cbccc7e
diff --git a/cc/linker.go b/cc/linker.go
index 4619926..07d9aa8 100644
--- a/cc/linker.go
+++ b/cc/linker.go
@@ -156,6 +156,10 @@
 		}
 	}
 
+	if ctx.Os() == android.Windows {
+		deps.LateStaticLibs = append(deps.LateStaticLibs, "libwinpthread")
+	}
+
 	return deps
 }