resolv: Move ns_name_skip to its own file and into libc (bug 28091)

And reformat to GNU style.  Avoid out-of-bounds pointer arithmetic.
This also results in a fix of bug 28091 due to the additional packet
length checks.

The symbol was moved using scripts/move-symbol-to-libc.py.

Reviewed-by: Carlos O'Donell <carlos@systemhalted.org>

sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist

@@ -2578,6 +2578,7 @@ GLIBC_2.34 mtx_timedlock F
 GLIBC_2.34 mtx_trylock F
 GLIBC_2.34 mtx_unlock F
 GLIBC_2.34 ns_name_ntop F
+GLIBC_2.34 ns_name_skip F
 GLIBC_2.34 ns_name_unpack F
 GLIBC_2.34 openpty F
 GLIBC_2.34 posix_spawn_file_actions_addclosefrom_np F
@@ -3040,5 +3041,6 @@ GLIBC_2.9 dup3 F
 GLIBC_2.9 epoll_create1 F
 GLIBC_2.9 inotify_init1 F
 GLIBC_2.9 ns_name_ntop F
+GLIBC_2.9 ns_name_skip F
 GLIBC_2.9 ns_name_unpack F
 GLIBC_2.9 pipe2 F

sysdeps/unix/sysv/linux/sparc/sparc32/libresolv.abilist

@@ -80,7 +80,6 @@ GLIBC_2.9 ns_name_ntol F
 GLIBC_2.9 ns_name_pack F
 GLIBC_2.9 ns_name_pton F
 GLIBC_2.9 ns_name_rollback F
-GLIBC_2.9 ns_name_skip F
 GLIBC_2.9 ns_name_uncompress F
 GLIBC_2.9 ns_parse_ttl F
 GLIBC_2.9 ns_parserr F

sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist

@@ -2413,6 +2413,7 @@ GLIBC_2.34 mtx_timedlock F
 GLIBC_2.34 mtx_trylock F
 GLIBC_2.34 mtx_unlock F
 GLIBC_2.34 ns_name_ntop F
+GLIBC_2.34 ns_name_skip F
 GLIBC_2.34 ns_name_unpack F
 GLIBC_2.34 openpty F
 GLIBC_2.34 posix_spawn_file_actions_addclosefrom_np F
@@ -2680,5 +2681,6 @@ GLIBC_2.9 dup3 F
 GLIBC_2.9 epoll_create1 F
 GLIBC_2.9 inotify_init1 F
 GLIBC_2.9 ns_name_ntop F
+GLIBC_2.9 ns_name_skip F
 GLIBC_2.9 ns_name_unpack F
 GLIBC_2.9 pipe2 F

sysdeps/unix/sysv/linux/sparc/sparc64/libresolv.abilist

@@ -80,7 +80,6 @@ GLIBC_2.9 ns_name_ntol F
 GLIBC_2.9 ns_name_pack F
 GLIBC_2.9 ns_name_pton F
 GLIBC_2.9 ns_name_rollback F
-GLIBC_2.9 ns_name_skip F
 GLIBC_2.9 ns_name_uncompress F
 GLIBC_2.9 ns_parse_ttl F
 GLIBC_2.9 ns_parserr F