Remove configure check LOG1P_DROPS_ZERO_SIGN. (GH-9193)

It is unused.

<!--
Thanks for your contribution!
Please read this comment in its entirety. It's quite important.

# Pull Request title

It should be in the following format:

```
bpo-NNNN: Summary of the changes made
```

Where: bpo-NNNN refers to the issue number in the https://bugs.python.org.

Most PRs will require an issue number. Trivial changes, like fixing a typo, do not need an issue.

# Backport Pull Request title

If this is a backport PR (PR made against branches other than `master`),
please ensure that the PR title is in the following format:

```
[X.Y] <title from the original PR> (GH-NNNN)
```

Where: [X.Y] is the branch name, e.g. [3.6].

GH-NNNN refers to the PR number from `master`.

-->

1 files changed, 0 insertions, 51 deletions

diff --git a/configure b/configure
index b4a70e6736..9520446d5d 100755
--- a/configure
+++ b/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