Implement pthread_sigqueue.

Bug: http://b/112770187
Test: bionic-unit-tests
Change-Id: I03382cd5df2490b2e87265dba9007e2cb1b14cd2
diff --git a/libc/Android.bp b/libc/Android.bp
index 61d00cd..fe65ace 100644
--- a/libc/Android.bp
+++ b/libc/Android.bp
@@ -1456,6 +1456,7 @@
         "bionic/pthread_mutex.cpp",
         "bionic/pthread_once.cpp",
         "bionic/pthread_rwlock.cpp",
+        "bionic/pthread_sigqueue.cpp",
         "bionic/pthread_self.cpp",
         "bionic/pthread_setname_np.cpp",
         "bionic/pthread_setschedparam.cpp",