[newlib-cygwin] Fix strtof ("-nan") returns positive NaN

[Corinna Vinschen <corinna at sourceware dot org>]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=c8d4c99ecd84efb9f47d2af7ce52d5996d17d4a4

commit c8d4c99ecd84efb9f47d2af7ce52d5996d17d4a4
Author: Masamichi Hosoda <trueroad@trueroad.jp>
Date:   Wed Aug 15 08:39:22 2018 +0900

    Fix strtof ("-nan") returns positive NaN
    
    strtof ("-nan") returned positive NaN instead of negative NaN.
    strtod ("-nan") and strtold ("-nan") return negative NaN.
    
    Linux glibc has been fixed
    that strto{f|d|ld} ("-nan") returns negative NaN.
    https://sourceware.org/bugzilla/show_bug.cgi?id=23007
    
    This commit makes strtof preserves the negative sign bit
    when parsing "-nan" like glibc.

Diff:
---
 newlib/libc/stdlib/strtod.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/newlib/libc/stdlib/strtod.c b/newlib/libc/stdlib/strtod.c
index 3164e30..431d3ab 100644
--- a/newlib/libc/stdlib/strtod.c
+++ b/newlib/libc/stdlib/strtod.c
@@ -1289,7 +1289,7 @@ strtof_l (const char *__restrict s00, char **__restrict se, locale_t loc)
 {
   double val = _strtod_l (_REENT, s00, se, loc);
   if (isnan (val))
-    return nanf (NULL);
+    return signbit (val) ? -nanf (NULL) : nanf (NULL);
   float retval = (float) val;
 #ifndef NO_ERRNO
   if (isinf (retval) && !isinf (val))
@@ -1304,7 +1304,7 @@ strtof (const char *__restrict s00,
 {
   double val = _strtod_l (_REENT, s00, se, __get_current_locale ());
   if (isnan (val))
-    return nanf (NULL);
+    return signbit (val) ? -nanf (NULL) : nanf (NULL);
   float retval = (float) val;
 #ifndef NO_ERRNO
   if (isinf (retval) && !isinf (val))