[glibc/maskray/unnest] Do not define tgmath.h fmaxmag, fminmag macros for C2X (bug 28397)

[glibc/maskray/unnest] Do not define tgmath.h fmaxmag, fminmag macros for C2X (bug 28397)

[Fangrui Song]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=79850e1025aabeccd3586c32ca259aa854607582

commit 79850e1025aabeccd3586c32ca259aa854607582
Author: Joseph Myers <joseph@codesourcery.com>
Date:   Wed Sep 29 17:38:32 2021 +0000

    Do not define tgmath.h fmaxmag, fminmag macros for C2X (bug 28397)
    
    C2X does not include fmaxmag and fminmag.  When I updated feature test
    macro handling accordingly (commit
    858045ad1c5ac1682288bbcb3676632b97a21ddf, "Update floating-point
    feature test macro handling for C2X", included in 2.34), I missed
    updating tgmath.h so it doesn't define the corresponding type-generic
    macros unless __STDC_WANT_IEC_60559_BFP_EXT__ is defined; I've now
    reported this as bug 28397.  Adjust the conditionals in tgmath.h
    accordingly.
    
    Tested for x86_64.

Diff:
---
 math/tgmath.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/math/tgmath.h b/math/tgmath.h
index 9868353c46..3d7b0998df 100644
--- a/math/tgmath.h
+++ b/math/tgmath.h
@@ -921,7 +921,9 @@
 
 /* Like ilogb, but returning long int.  */
 # define llogb(Val) __TGMATH_UNARY_REAL_RET_ONLY (Val, llogb)
+#endif
 
+#if __GLIBC_USE (IEC_60559_BFP_EXT)
 /* Return value with maximum magnitude.  */
 # define fmaxmag(Val1, Val2) __TGMATH_BINARY_REAL_ONLY (Val1, Val2, fmaxmag)