Use the canonical idiom for sockaddr_storage.

This works out a bit silly/ugly because the bits/ header file has the
wrong name, so I've also changed the map from kernel struct to boolean
to be a map from kernel struct to filename. That not only fixes this,
it's a bit more readable too. (Just yesterday, when I had no real reason
to change it, I was asking myself "why is this a boolean?"!)

Bug: http://b/236042740
Test: treehugger
Change-Id: I3eee25b493ea97d46cc5dc5fde07f7c5e77d2a46
diff --git a/libc/kernel/uapi/linux/in.h b/libc/kernel/uapi/linux/in.h
index e784690..44efdd8 100644
--- a/libc/kernel/uapi/linux/in.h
+++ b/libc/kernel/uapi/linux/in.h
@@ -148,32 +148,32 @@
 #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 {
   union {
     struct {
       __u32 gf_interface_aux;
-      struct __kernel_sockaddr_storage gf_group_aux;
+      struct sockaddr_storage gf_group_aux;
       __u32 gf_fmode_aux;
       __u32 gf_numsrc_aux;
-      struct __kernel_sockaddr_storage gf_slist[1];
+      struct sockaddr_storage gf_slist[1];
     };
     struct {
       __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_flex[];
+      struct sockaddr_storage gf_slist_flex[];
     };
   };
 };
-#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 {