[gcc r16-647] libstdc++: Fix preprocessor check for __float128 formatter [PR119246]

[Tomasz Kaminski]

https://gcc.gnu.org/g:d010a39b9e788a1b3c58e0954c1b2c6afad8210a

commit r16-647-gd010a39b9e788a1b3c58e0954c1b2c6afad8210a
Author: Tomasz Kamiński <tkaminsk@redhat.com>
Date:   Thu May 15 08:58:09 2025 +0200

    libstdc++: Fix preprocessor check for __float128 formatter [PR119246]
    
    The previous check `_GLIBCXX_FORMAT_F128 != 1` was passing if
    _GLIBCXX_FORMAT_F128 was not defined, i.e. evaluted to zero.
    
    This broke sparc-sun-solaris2.11 and x86_64-darwin.
    
            PR libstdc++/119246
    
    libstdc++-v3/ChangeLog:
    
            * include/std/format: Updated check for _GLIBCXX_FORMAT_F128.

Diff:
---
 libstdc++-v3/include/std/format | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libstdc++-v3/include/std/format b/libstdc++-v3/include/std/format
index f0b0252255d3..bfda5895e0c0 100644
--- a/libstdc++-v3/include/std/format
+++ b/libstdc++-v3/include/std/format
@@ -2973,7 +2973,7 @@ namespace __format
     };
 #endif
 
-#if defined(__SIZEOF_FLOAT128__) && _GLIBCXX_FORMAT_F128 != 1
+#if defined(__SIZEOF_FLOAT128__) && _GLIBCXX_FORMAT_F128 > 1
   // Reuse __formatter_fp<C>::format<__format::__flt128_t, Out> for __float128.
   // This formatter is not declared if _GLIBCXX_LONG_DOUBLE_ALT128_COMPAT is true,
   // as __float128 when present is same type as __ieee128, which may be same as