Remove configure check LOG1P_DROPS_ZERO_SIGN. (pythonGH-9193)

It is unused.

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aclocal.m4

@@ -1,6 +1,6 @@
-# generated automatically by aclocal 1.15 -*- Autoconf -*-
+# generated automatically by aclocal 1.15.1 -*- Autoconf -*-
 
-# Copyright (C) 1996-2014 Free Software Foundation, Inc.
+# Copyright (C) 1996-2017 Free Software Foundation, Inc.
 
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,

configure

@@ -13688,7 +13688,6 @@ fi
 
 
 
-
 # checks for system services
 # (none yet)
 
@@ -14209,56 +14208,6 @@ then
 $as_echo "#define TANH_PRESERVES_ZERO_SIGN 1" >>confdefs.h
 
 fi
-
-if test "$ac_cv_func_log1p" = yes
-then
-    # On some versions of AIX, log1p(-0.) returns 0. instead of
-    # -0.  See issue #9920.
-    { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether log1p drops the sign of negative zero" >&5
-$as_echo_n "checking whether log1p drops the sign of negative zero... " >&6; }
-    if ${ac_cv_log1p_drops_zero_sign+:} false; then :
-  $as_echo_n "(cached) " >&6
-else
-
-    if test "$cross_compiling" = yes; then :
-  ac_cv_log1p_drops_zero_sign=no
-else
-  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-
-    #include <math.h>
-    #include <stdlib.h>
-    int main() {
-        /* Fail if the signs of log1p(-0.) and -0. can be
-	   distinguished. */
-        if (atan2(log1p(-0.), -1.) == atan2(-0., -1.))
-            return 0;
-        else
-            return 1;
-    }
-
-_ACEOF
-if ac_fn_c_try_run "$LINENO"; then :
-  ac_cv_log1p_drops_zero_sign=no
-else
-  ac_cv_log1p_drops_zero_sign=yes
-fi
-rm -f core *.core core.conftest.* gmon.out bb.out conftest$ac_exeext \
-  conftest.$ac_objext conftest.beam conftest.$ac_ext
-fi
-
-fi
-
-    { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_log1p_drops_zero_sign" >&5
-$as_echo "$ac_cv_log1p_drops_zero_sign" >&6; }
-fi
-if test "$ac_cv_log1p_drops_zero_sign" = yes
-then
-
-$as_echo "#define LOG1P_DROPS_ZERO_SIGN 1" >>confdefs.h
-
-fi
-
 LIBS=$LIBS_SAVE
 
 # For multiprocessing module, check that sem_open

configure.ac

@@ -4384,36 +4384,6 @@ then
   AC_DEFINE(TANH_PRESERVES_ZERO_SIGN, 1,
   [Define if tanh(-0.) is -0., or if platform doesn't have signed zeros])
 fi
-
-if test "$ac_cv_func_log1p" = yes
-then
-    # On some versions of AIX, log1p(-0.) returns 0. instead of
-    # -0.  See issue #9920.
-    AC_MSG_CHECKING(whether log1p drops the sign of negative zero)
-    AC_CACHE_VAL(ac_cv_log1p_drops_zero_sign, [
-    AC_RUN_IFELSE([AC_LANG_SOURCE([[
-    #include <math.h>
-    #include <stdlib.h>
-    int main() {
-        /* Fail if the signs of log1p(-0.) and -0. can be
-	   distinguished. */
-        if (atan2(log1p(-0.), -1.) == atan2(-0., -1.))
-            return 0;
-        else
-            return 1;
-    }
-    ]])],
-    [ac_cv_log1p_drops_zero_sign=no],
-    [ac_cv_log1p_drops_zero_sign=yes],
-    [ac_cv_log1p_drops_zero_sign=no])])
-    AC_MSG_RESULT($ac_cv_log1p_drops_zero_sign)
-fi
-if test "$ac_cv_log1p_drops_zero_sign" = yes
-then
-  AC_DEFINE(LOG1P_DROPS_ZERO_SIGN, 1,
-  [Define if log1p(-0.) is 0. rather than -0.])
-fi
-
 LIBS=$LIBS_SAVE
 
 # For multiprocessing module, check that sem_open

pyconfig.h.in

@@ -1285,9 +1285,6 @@
 /* Define to 1 if you have the `_getpty' function. */
 #undef HAVE__GETPTY
 
-/* Define if log1p(-0.) is 0. rather than -0. */
-#undef LOG1P_DROPS_ZERO_SIGN
-
 /* Define to 1 if `major', `minor', and `makedev' are declared in <mkdev.h>.
    */
 #undef MAJOR_IN_MKDEV