Remove vestiges of external build support from libio headers.

As requested by Adhemerval, this patch removes some preprocessor
conditionals from the libio headers that were only relevant when
building libio outside glibc.

Installed stripped libraries and executables are unchanged by this
patch.

	* libio/iolibio.h, libio/libioP.h: Remove extern "C".
	* libio/libio.h: Remove __BEGIN_DECLS and __END_DECLS.
	Remove preprocessor conditionals on _LIBC and __USE_GNU,
	which are always true, and __cplusplus, which is always false.

4 files changed, 12 insertions, 43 deletions

diff --git a/ChangeLog b/ChangeLog
index 64d0cfaa7a..a1ecade870 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2018-02-21  Zack Weinberg  <zackw@panix.com>
+
+	* libio/iolibio.h, libio/libioP.h: Remove extern "C".
+	* libio/libio.h: Remove __BEGIN_DECLS and __END_DECLS.
+	Remove preprocessor conditionals on _LIBC and __USE_GNU,
+	which are always true, and __cplusplus, which is always false.
+
 2018-02-21  Joseph Myers  <joseph@codesourcery.com>
 
 	[BZ #15105]
diff --git a/libio/iolibio.h b/libio/iolibio.h
index 52731b65f9..4d43d0e72d 100644
--- a/libio/iolibio.h
+++ b/libio/iolibio.h
@@ -7,10 +7,6 @@
 /* These emulate stdio functionality, but with a different name
    (_IO_ungetc instead of ungetc), and using _IO_FILE instead of FILE. */
 
-#ifdef __cplusplus
-extern "C" {
-#endif
-
 extern int _IO_fclose (_IO_FILE*);
 extern int _IO_new_fclose (_IO_FILE*);
 extern int _IO_old_fclose (_IO_FILE*);
@@ -95,8 +91,4 @@ extern int __old_pclose (_IO_FILE *) __THROW;
 _IO_FILE *__new_freopen (const char *, const char *, _IO_FILE *) __THROW;
 _IO_FILE *__old_freopen (const char *, const char *, _IO_FILE *) __THROW;
 
-#ifdef __cplusplus
-}
-#endif
-
 #endif /* iolibio.h.  */
diff --git a/libio/libio.h b/libio/libio.h
index 0953120247..7a68e1a3ae 100644
--- a/libio/libio.h
+++ b/libio/libio.h
@@ -73,8 +73,6 @@ typedef union
 
 #include <shlib-compat.h>
 
-__BEGIN_DECLS
-
 /* compatibility defines */
 #define _STDIO_USES_IOSTREAM
 #define _IO_UNIFIED_JUMPTABLES 1
@@ -119,16 +117,12 @@ __BEGIN_DECLS
 
 #define _IO_FLAGS2_MMAP 1
 #define _IO_FLAGS2_NOTCANCEL 2
-#ifdef _LIBC
-# define _IO_FLAGS2_FORTIFY 4
-#endif
+#define _IO_FLAGS2_FORTIFY 4
 #define _IO_FLAGS2_USER_WBUF 8
-#ifdef _LIBC
-# define _IO_FLAGS2_SCANF_STD 16
-# define _IO_FLAGS2_NOCLOSE 32
-# define _IO_FLAGS2_CLOEXEC 64
-# define _IO_FLAGS2_NEED_LOCK 128
-#endif
+#define _IO_FLAGS2_SCANF_STD 16
+#define _IO_FLAGS2_NOCLOSE 32
+#define _IO_FLAGS2_CLOEXEC 64
+#define _IO_FLAGS2_NEED_LOCK 128
 
 /* These are "formatting flags" matching the iostream fmtflags enum values. */
 #define _IO_SKIPWS 01
@@ -227,29 +221,18 @@ struct _IO_wide_data
   const struct _IO_jump_t *_wide_vtable;
 };
 
-
-#ifndef __cplusplus
 typedef struct _IO_FILE _IO_FILE;
-#endif
 
 struct _IO_FILE_plus;
 
 extern struct _IO_FILE_plus _IO_2_1_stdin_;
 extern struct _IO_FILE_plus _IO_2_1_stdout_;
 extern struct _IO_FILE_plus _IO_2_1_stderr_;
-#ifndef _LIBC
-#define _IO_stdin ((_IO_FILE*)(&_IO_2_1_stdin_))
-#define _IO_stdout ((_IO_FILE*)(&_IO_2_1_stdout_))
-#define _IO_stderr ((_IO_FILE*)(&_IO_2_1_stderr_))
-#else
 extern _IO_FILE *_IO_stdin attribute_hidden;
 extern _IO_FILE *_IO_stdout attribute_hidden;
 extern _IO_FILE *_IO_stderr attribute_hidden;
-#endif
-
 
 /* Compatibility names for cookie I/O functions.  */
-#ifdef __USE_GNU
 typedef cookie_read_function_t __io_read_fn;
 typedef cookie_write_function_t __io_write_fn;
 typedef cookie_seek_function_t __io_seek_fn;
@@ -261,7 +244,6 @@ struct _IO_cookie_file;
 /* Initialize one of those.  */
 extern void _IO_cookie_init (struct _IO_cookie_file *__cfile, int __read_write,
 			     void *__cookie, _IO_cookie_io_functions_t __fns);
-#endif
 
 extern int __underflow (_IO_FILE *);
 extern _IO_wint_t __wunderflow (_IO_FILE *);
@@ -342,8 +324,6 @@ extern _IO_wint_t _IO_getwc (_IO_FILE *__fp);
 extern _IO_wint_t _IO_putwc (wchar_t __wc, _IO_FILE *__fp);
 extern int _IO_fwide (_IO_FILE *__fp, int __mode) __THROW;
 
-/* While compiling glibc we have to handle compatibility with very old
-   versions.  */
 #if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_1)
 #  define _IO_fwide_maybe_incompatible \
   (__builtin_expect (&_IO_stdin_used == NULL, 0))
@@ -416,6 +396,4 @@ libc_hidden_proto (_IO_vfscanf)
 # endif
 #endif /* _IO_MTSAFE_IO */
 
-__END_DECLS
-
 #endif /* _LIBIO_H */
diff --git a/libio/libioP.h b/libio/libioP.h
index 58cc9de094..abbf331685 100644
--- a/libio/libioP.h
+++ b/libio/libioP.h
@@ -52,10 +52,6 @@
    adjusts the libio configuration.  */
 #include <_G_config.h>
 
-#ifdef __cplusplus
-extern "C" {
-#endif
-
 #define _IO_seek_set 0
 #define _IO_seek_cur 1
 #define _IO_seek_end 2
@@ -731,10 +727,6 @@ extern int _IO_vscanf (const char *, _IO_va_list) __THROW;
 # define _IO_pos_0 ((_IO_off64_t) 0)
 #endif
 
-#ifdef __cplusplus
-}
-#endif
-
 #ifdef _IO_MTSAFE_IO
 /* check following! */
 # ifdef _IO_USE_OLD_IO_FILE