Update to kernel headers v4.12.3.

Test: Built angler.
Change-Id: Icbcf4fac2334de8409b049ed7a3b4c24b4e98ce9
diff --git a/libc/kernel/uapi/linux/rpmsg.h b/libc/kernel/uapi/linux/rpmsg.h
new file mode 100644
index 0000000..77f05e6
--- /dev/null
+++ b/libc/kernel/uapi/linux/rpmsg.h
@@ -0,0 +1,30 @@
+/****************************************************************************
+ ****************************************************************************
+ ***
+ ***   This header was automatically generated from a Linux kernel header
+ ***   of the same name, to make information necessary for userspace to
+ ***   call into the kernel available to libc.  It contains only constants,
+ ***   structures, and macros generated from the original header, and thus,
+ ***   contains no copyrightable information.
+ ***
+ ***   To edit the content of this header, modify the corresponding
+ ***   source file (e.g. under external/kernel-headers/original/) then
+ ***   run bionic/libc/kernel/tools/update_all.py
+ ***
+ ***   Any manual change here will be lost the next time this script will
+ ***   be run. You've been warned!
+ ***
+ ****************************************************************************
+ ****************************************************************************/
+#ifndef _UAPI_RPMSG_H_
+#define _UAPI_RPMSG_H_
+#include <linux/ioctl.h>
+#include <linux/types.h>
+struct rpmsg_endpoint_info {
+  char name[32];
+  __u32 src;
+  __u32 dst;
+};
+#define RPMSG_CREATE_EPT_IOCTL _IOW(0xb5, 0x1, struct rpmsg_endpoint_info)
+#define RPMSG_DESTROY_EPT_IOCTL _IO(0xb5, 0x2)
+#endif