Add autoconf test to detect x87-style double rounding, as described in
issue #2937. This information can be helpful for diagnosing platform-
specific problems in math and cmath. The result of the test also
serves as a fairly reliable indicator of whether the x87 floating-point
instructions (as opposed to SSE2) are in use on Intel x86/x86_64 systems.
diff --git a/pyconfig.h.in b/pyconfig.h.in
index 4075d14..e3fb0a5 100644
--- a/pyconfig.h.in
+++ b/pyconfig.h.in
@@ -983,6 +983,9 @@
first (like Motorola and SPARC, unlike Intel and VAX). */
#undef WORDS_BIGENDIAN
+/* Define if arithmetic is subject to x87-style double rounding issue */
+#undef X87_DOUBLE_ROUNDING
+
/* Define to 1 if on AIX 3.
System headers sometimes define this.
We just want to avoid a redefinition error message. */