[gcc r12-2471] aix: Protect AIX math.h overloads with new macro.

[gcc r12-2471] aix: Protect AIX math.h overloads with new macro.

[David Edelsohn]

https://gcc.gnu.org/g:3f7a2374d312112ea9a858dbbb883edf50730e96

commit r12-2471-g3f7a2374d312112ea9a858dbbb883edf50730e96
Author: David Edelsohn <dje.gcc@gmail.com>
Date:   Wed Jul 21 14:06:45 2021 -0400

    aix: Protect AIX math.h overloads with new macro.
    
    AIX math.h provides C++ overloaded inlined math functions, which should
    not be present for G++. The definitions have been guaded by
    __COMPATMATH__, but that macro had other uses in IBM xlC++. A new
    macro has been introduced with the sole purpose of guarding the functions.
    This patch updates libstdc++ os_defines.h to define the additional macro.
    The earlier macro definition is retained to guard the functions in the
    math.h header of earlier AIX releases.
    
    libstdc++-v3/ChangeLog:
    
            * config/os/aix/os_defines.h (__LIBC_NO_CPP_MATH_OVERLOADS__): Define.

Diff:
---
 libstdc++-v3/config/os/aix/os_defines.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/libstdc++-v3/config/os/aix/os_defines.h b/libstdc++-v3/config/os/aix/os_defines.h
index 723a6533319..265e2941d1a 100644
--- a/libstdc++-v3/config/os/aix/os_defines.h
+++ b/libstdc++-v3/config/os/aix/os_defines.h
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-3.0-or-later WITH GCC-exception-3.1
 // Specific definitions for AIX  -*- C++ -*-
 
 // Copyright (C) 2000-2021 Free Software Foundation, Inc.
@@ -48,6 +49,10 @@
 #define __COMPATMATH__
 #endif
 
+#ifndef __LIBC_NO_CPP_MATH_OVERLOADS__
+#define __LIBC_NO_CPP_MATH_OVERLOADS__
+#endif
+
 // No support for referencing weak symbols without a definition.
 #define _GLIBCXX_USE_WEAK_REF 0