[gcc r13-4178] libstdc++: Add std qualification on isxdigit calls

[Francois Dumont]

https://gcc.gnu.org/g:a16a5460447eaaff0b4468064e4d7b1cc8fc42eb

commit r13-4178-ga16a5460447eaaff0b4468064e4d7b1cc8fc42eb
Author: François Dumont <fdumont@gcc.gnu.org>
Date:   Sat Nov 19 13:51:45 2022 +0100

    libstdc++: Add std qualification on isxdigit calls
    
    Those qualifications are needed in _GLIBCXX_INLINE_VERSION mode because in <cctype>
    symbols are not put in versioned namespace.
    
    libstdc++-v3/ChangeLog
    
            * include/std/format: Add std qualification on isxdigit calls.

Diff:
---
 libstdc++-v3/include/std/format | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/libstdc++-v3/include/std/format b/libstdc++-v3/include/std/format
index 561ae161d16..7ae58eb2416 100644
--- a/libstdc++-v3/include/std/format
+++ b/libstdc++-v3/include/std/format
@@ -1537,7 +1537,7 @@ namespace __format
 
 	      if (__trailing_zeros)
 		{
-		  if (!isxdigit(__s[0]))
+		  if (!std::isxdigit(__s[0]))
 		    --__sigfigs;
 		  __z = __prec - __sigfigs;
 		}
@@ -1627,7 +1627,7 @@ namespace __format
 		{
 		  __fill_char = _CharT('0');
 		  // Write sign before zero filling.
-		  if (!isxdigit(__narrow_str[0]))
+		  if (!std::isxdigit(__narrow_str[0]))
 		    {
 		      *__out++ = __str[0];
 		      __str.remove_prefix(1);