Implemented pthread_atfork()

Change-Id: Ie6c0bf593315d3507b3c4a6c8903a74a1fa053db
diff --git a/libc/Android.mk b/libc/Android.mk
index 7a7d9e3..568cc94 100644
--- a/libc/Android.mk
+++ b/libc/Android.mk
@@ -324,6 +324,7 @@
 # up any thumb code.
 libc_common_src_files += \
 	bionic/pthread.c.arm \
+	bionic/pthread-atfork.c.arm \
 	bionic/pthread-timers.c.arm \
 	bionic/ptrace.c.arm
 
@@ -358,6 +359,7 @@
 	arch-x86/string/strncmp_wrapper.S \
 	arch-x86/string/strlen.S \
 	bionic/pthread.c \
+	bionic/pthread-atfork.c \
 	bionic/pthread-timers.c \
 	bionic/ptrace.c
 
@@ -394,6 +396,7 @@
 	string/memcmp.c \
 	string/strlen.c \
 	bionic/pthread.c \
+	bionic/pthread-atfork.c \
 	bionic/pthread-timers.c \
 	bionic/ptrace.c \
 	unistd/socketcalls.c