Use in_addr in ip_mreq_source and ip_msfilter.

This adds a new mechanism to say "replace struct S with #include <bits/S.h>".

Also switch epoll_event over to the new mechanism.

Also use the kernel's struct sockaddr_storage directly rather than behind
an unnecessary #define.

This patch also removes some dead code in the header scrubber. This code
still needs rewriting completely. I learned that a "block" isn't necessarily
a single struct definition, say; it might be a run of them. It seems like
a block is a run of preprocessor directives or a run of regular code.

Bug: https://issuetracker.google.com/36987220
Test: new test
Change-Id: Ic6a5c09559766a4babe3cd4c3ea538b885e07308
diff --git a/libc/kernel/uapi/linux/in.h b/libc/kernel/uapi/linux/in.h
index 351126a..788a6d9 100644
--- a/libc/kernel/uapi/linux/in.h
+++ b/libc/kernel/uapi/linux/in.h
@@ -18,6 +18,9 @@
  ****************************************************************************/
 #ifndef _UAPI_LINUX_IN_H
 #define _UAPI_LINUX_IN_H
+#include <bits/ip_msfilter.h>
+#include <bits/ip_mreq_source.h>
+#include <bits/in_addr.h>
 #include <linux/types.h>
 #include <linux/libc-compat.h>
 #include <linux/socket.h>
@@ -77,9 +80,6 @@
 };
 #endif
 #if __UAPI_DEF_IN_ADDR
-struct in_addr {
-  __be32 s_addr;
-};
 #endif
 #define IP_TOS 1
 #define IP_TTL 2
@@ -147,36 +147,24 @@
   struct in_addr imr_address;
   int imr_ifindex;
 };
-struct ip_mreq_source {
-  __be32 imr_multiaddr;
-  __be32 imr_interface;
-  __be32 imr_sourceaddr;
-};
-struct ip_msfilter {
-  __be32 imsf_multiaddr;
-  __be32 imsf_interface;
-  __u32 imsf_fmode;
-  __u32 imsf_numsrc;
-  __be32 imsf_slist[1];
-};
 #define IP_MSFILTER_SIZE(numsrc) (sizeof(struct ip_msfilter) - sizeof(__u32) + (numsrc) * sizeof(__u32))
 struct group_req {
   __u32 gr_interface;
-  struct __kernel_sockaddr_storage gr_group;
+  struct sockaddr_storage gr_group;
 };
 struct group_source_req {
   __u32 gsr_interface;
-  struct __kernel_sockaddr_storage gsr_group;
-  struct __kernel_sockaddr_storage gsr_source;
+  struct sockaddr_storage gsr_group;
+  struct sockaddr_storage gsr_source;
 };
 struct group_filter {
   __u32 gf_interface;
-  struct __kernel_sockaddr_storage gf_group;
+  struct sockaddr_storage gf_group;
   __u32 gf_fmode;
   __u32 gf_numsrc;
-  struct __kernel_sockaddr_storage gf_slist[1];
+  struct sockaddr_storage gf_slist[1];
 };
-#define GROUP_FILTER_SIZE(numsrc) (sizeof(struct group_filter) - sizeof(struct __kernel_sockaddr_storage) + (numsrc) * sizeof(struct __kernel_sockaddr_storage))
+#define GROUP_FILTER_SIZE(numsrc) (sizeof(struct group_filter) - sizeof(struct sockaddr_storage) + (numsrc) * sizeof(struct sockaddr_storage))
 #endif
 #if __UAPI_DEF_IN_PKTINFO
 struct in_pktinfo {