resolv: Move dn_comp to its own file and into libc

And reformat it to GNU style.

dn_comp is used in various programs, so keep it as a non-deprecated
symbol.  Switch to dn_comp (not __dn_comp) for the ABI name.  There
are no internal users, so interposition is not a problem.

The __dn_comp symbol was moved with scripts/move-symbol-to-libc.py
--no-new-version.  dn_comp@@GLIBC_2.34 was added with
make update-all-abi.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>

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

@@ -127,6 +127,7 @@ GLIBC_2.0 __default_morecore F
 GLIBC_2.0 __deregister_frame F
 GLIBC_2.0 __deregister_frame_info F
 GLIBC_2.0 __dgettext F
+GLIBC_2.0 __dn_comp F
 GLIBC_2.0 __dup2 F
 GLIBC_2.0 __environ D 0x4
 GLIBC_2.0 __errno_location F
@@ -2551,6 +2552,7 @@ GLIBC_2.34 dlmopen F
 GLIBC_2.34 dlopen F
 GLIBC_2.34 dlsym F
 GLIBC_2.34 dlvsym F
+GLIBC_2.34 dn_comp F
 GLIBC_2.34 dn_expand F
 GLIBC_2.34 execveat F
 GLIBC_2.34 forkpty F

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

@@ -1,6 +1,5 @@
 GLIBC_2.0 __b64_ntop F
 GLIBC_2.0 __b64_pton F
-GLIBC_2.0 __dn_comp F
 GLIBC_2.0 __dn_count_labels F
 GLIBC_2.0 __dn_skipname F
 GLIBC_2.0 __fp_nquery F

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

@@ -2,6 +2,7 @@ GCC_3.0 _Unwind_Find_FDE F
 GCC_3.0 __deregister_frame_info_bases F
 GCC_3.0 __register_frame_info_bases F
 GCC_3.0 __register_frame_info_table_bases F
+GLIBC_2.0 __dn_comp F
 GLIBC_2.0 dladdr F
 GLIBC_2.0 dlclose F
 GLIBC_2.0 dlerror F
@@ -2386,6 +2387,7 @@ GLIBC_2.34 dlmopen F
 GLIBC_2.34 dlopen F
 GLIBC_2.34 dlsym F
 GLIBC_2.34 dlvsym F
+GLIBC_2.34 dn_comp F
 GLIBC_2.34 dn_expand F
 GLIBC_2.34 execveat F
 GLIBC_2.34 forkpty F

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

@@ -1,6 +1,5 @@
 GLIBC_2.0 __b64_ntop F
 GLIBC_2.0 __b64_pton F
-GLIBC_2.0 __dn_comp F
 GLIBC_2.0 __dn_count_labels F
 GLIBC_2.0 __dn_skipname F
 GLIBC_2.0 __fp_nquery F