[newlib-cygwin] libm/common: Set WANT_ERRNO based on _IEEE_LIBM value

[Corinna Vinschen <corinna@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=bb166cfc3e45ceb712fb867c116b7cae4834209d

commit bb166cfc3e45ceb712fb867c116b7cae4834209d
Author: Keith Packard via Newlib <newlib@sourceware.org>
Date:   Mon Aug 3 10:55:03 2020 -0700

    libm/common: Set WANT_ERRNO based on _IEEE_LIBM value
    
    _IEEE_LIBM is the configuration value which controls whether the
    original libm functions modify errno. Use that in the new math code as
    well so that the resulting library is internally consistent.
    
    Signed-off-by: Keith Packard <keithp@keithp.com>

Diff:
---
 newlib/libm/common/math_config.h | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/newlib/libm/common/math_config.h b/newlib/libm/common/math_config.h
index 1a2d0f639..3be7e6320 100644
--- a/newlib/libm/common/math_config.h
+++ b/newlib/libm/common/math_config.h
@@ -36,7 +36,9 @@
 /* Correct special case results in non-nearest rounding modes.  */
 # define WANT_ROUNDING 1
 #endif
-#ifndef WANT_ERRNO
+#ifdef _IEEE_LIBM
+# define WANT_ERRNO 0
+#else
 /* Set errno according to ISO C with (math_errhandling & MATH_ERRNO) != 0.  */
 # define WANT_ERRNO 1
 #endif