Update Gnulib to 6835fc458f30b94f15d69c35a79cbc2dfabe2d06.

m4/extern-inline.m4

@@ -1,6 +1,6 @@
 dnl 'extern inline' a la ISO C99.
 
-dnl Copyright 2012-2014 Free Software Foundation, Inc.
+dnl Copyright 2012-2016 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
@@ -19,13 +19,28 @@ AC_DEFUN([gl_EXTERN_INLINE],
    'reference to static identifier "f" in extern inline function'.
    This bug was observed with Sun C 5.12 SunOS_i386 2011/11/16.
 
-   Suppress the use of extern inline on problematic Apple configurations.
-   OS X 10.8 and earlier mishandle it; see, e.g.,
-   <http://lists.gnu.org/archive/html/bug-gnulib/2012-12/msg00023.html>.
+   Suppress extern inline (with or without __attribute__ ((__gnu_inline__)))
+   on configurations that mistakenly use 'static inline' to implement
+   functions or macros in standard C headers like <ctype.h>.  For example,
+   if isdigit is mistakenly implemented via a static inline function,
+   a program containing an extern inline function that calls isdigit
+   may not work since the C standard prohibits extern inline functions
+   from calling static functions.  This bug is known to occur on:
+
+     OS X 10.8 and earlier; see:
+     http://lists.gnu.org/archive/html/bug-gnulib/2012-12/msg00023.html
+
+     DragonFly; see
+     http://muscles.dragonflybsd.org/bulk/bleeding-edge-potential/latest-per-pkg/ah-tty-0.3.12.log
+
+     FreeBSD; see:
+     http://lists.gnu.org/archive/html/bug-gnulib/2014-07/msg00104.html
+
    OS X 10.9 has a macro __header_inline indicating the bug is fixed for C and
    for clang but remains for g++; see <http://trac.macports.org/ticket/41033>.
-   Perhaps Apple will fix this some day.  */
-#if (defined __APPLE__ \
+   Assume DragonFly and FreeBSD will be similar.  */
+#if (((defined __APPLE__ && defined __MACH__) \
+      || defined __DragonFly__ || defined __FreeBSD__) \
      && (defined __header_inline \
          ? (defined __cplusplus && defined __GNUC_STDC_INLINE__ \
             && ! defined __clang__) \
@@ -33,19 +48,20 @@ AC_DEFUN([gl_EXTERN_INLINE],
              && (defined __GNUC__ || defined __cplusplus)) \
             || (defined _FORTIFY_SOURCE && 0 < _FORTIFY_SOURCE \
                 && defined __GNUC__ && ! defined __cplusplus))))
-# define _GL_EXTERN_INLINE_APPLE_BUG
+# define _GL_EXTERN_INLINE_STDHEADER_BUG
 #endif
 #if ((__GNUC__ \
       ? defined __GNUC_STDC_INLINE__ && __GNUC_STDC_INLINE__ \
       : (199901L <= __STDC_VERSION__ \
          && !defined __HP_cc \
+         && !defined __PGI \
          && !(defined __SUNPRO_C && __STDC__))) \
-     && !defined _GL_EXTERN_INLINE_APPLE_BUG)
+     && !defined _GL_EXTERN_INLINE_STDHEADER_BUG)
 # define _GL_INLINE inline
 # define _GL_EXTERN_INLINE extern inline
 # define _GL_EXTERN_INLINE_IN_USE
 #elif (2 < __GNUC__ + (7 <= __GNUC_MINOR__) && !defined __STRICT_ANSI__ \
-       && !defined _GL_EXTERN_INLINE_APPLE_BUG)
+       && !defined _GL_EXTERN_INLINE_STDHEADER_BUG)
 # if defined __GNUC_GNU_INLINE__ && __GNUC_GNU_INLINE__
    /* __gnu_inline__ suppresses a GCC 4.2 diagnostic.  */
 #  define _GL_INLINE extern inline __attribute__ ((__gnu_inline__))
@@ -59,17 +75,19 @@ AC_DEFUN([gl_EXTERN_INLINE],
 # define _GL_EXTERN_INLINE static _GL_UNUSED
 #endif
 
-#if 4 < __GNUC__ + (6 <= __GNUC_MINOR__)
+/* In GCC 4.6 (inclusive) to 5.1 (exclusive),
+   suppress bogus "no previous prototype for 'FOO'"
+   and "no previous declaration for 'FOO'" diagnostics,
+   when FOO is an inline function in the header; see
+   <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=54113> and
+   <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63877>.  */
+#if __GNUC__ == 4 && 6 <= __GNUC_MINOR__
 # if defined __GNUC_STDC_INLINE__ && __GNUC_STDC_INLINE__
 #  define _GL_INLINE_HEADER_CONST_PRAGMA
 # else
 #  define _GL_INLINE_HEADER_CONST_PRAGMA \
      _Pragma ("GCC diagnostic ignored \"-Wsuggest-attribute=const\"")
 # endif
-  /* Suppress GCC's bogus "no previous prototype for 'FOO'"
-     and "no previous declaration for 'FOO'"  diagnostics,
-     when FOO is an inline function in the header; see
-     <http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54113>.  */
 # define _GL_INLINE_HEADER_BEGIN \
     _Pragma ("GCC diagnostic push") \
     _Pragma ("GCC diagnostic ignored \"-Wmissing-prototypes\"") \