Avoid calling the undeclared exit function and future failures
with compilers which do not support implicit function declarations.

Submitted upstream: <https://savannah.gnu.org/bugs/index.php?63679>

diff --git a/configure b/configure
index b593652a6693e702..dac25375fd493823 100755
--- a/configure
+++ b/configure
@@ -14407,7 +14407,7 @@ int main (void)
    inf = exp(1.0e10);
    nan = inf / inf ;
    status = (nan == nan);
-   exit (status);
+   return status;
 }
 _ACEOF
 if ac_fn_c_try_run "$LINENO"
@@ -14452,7 +14452,7 @@ int main (void)
    for (i = 0; i < 5; i++) { z = z / 10.0 ; };
    for (i = 0; i < 5; i++) { z = z * 10.0 ; };
    status = (z == 0.0);
-   exit (status);
+   return status;
 }
 _ACEOF
 if ac_fn_c_try_run "$LINENO"
diff --git a/configure.ac b/configure.ac
index a2e038f5656e983a..40e7d2a3db3e4d41 100644
--- a/configure.ac
+++ b/configure.ac
@@ -449,7 +449,7 @@ int main (void)
    inf = exp(1.0e10);
    nan = inf / inf ;
    status = (nan == nan);
-   exit (status);
+   return status;
 }]])],[ac_cv_c_ieee_comparisons="yes"],[ac_cv_c_ieee_comparisons="no"],[ac_cv_c_ieee_comparisons="yes"])
 ])
 
@@ -469,7 +469,7 @@ int main (void)
    for (i = 0; i < 5; i++) { z = z / 10.0 ; };        
    for (i = 0; i < 5; i++) { z = z * 10.0 ; };
    status = (z == 0.0);
-   exit (status);
+   return status;
 }]])],[ac_cv_c_ieee_denormals="yes"],[ac_cv_c_ieee_denormals="no"],[ac_cv_c_ieee_denormals="yes"])
 ])