Initial OpenBSD support...

src/dtoa-config.c

Index: src/dtoa-config.c
===================================================================
--- src/dtoa-config.c	(revision 3397)
+++ src/dtoa-config.c	(working copy)
@@ -38,7 +38,7 @@
  */
 
 #if !(defined(__APPLE__) && defined(__MACH__)) && \
-    !defined(WIN32) && !defined(__FreeBSD__)
+    !defined(WIN32) && !defined(__FreeBSD__) && !defined(__OpenBSD__)
 #include <endian.h>
 #endif
 #include <math.h>
@@ -47,14 +47,16 @@
 /* The floating point word order on ARM is big endian when floating point
  * emulation is used, even if the byte order is little endian */
 #if !(defined(__APPLE__) && defined(__MACH__)) && !defined(WIN32) && \
-    !defined(__FreeBSD__) && __FLOAT_WORD_ORDER == __BIG_ENDIAN
+    !defined(__FreeBSD__) && !defined(__OpenBSD__) && \
+    __FLOAT_WORD_ORDER == __BIG_ENDIAN
 #define  IEEE_MC68k
 #else
 #define  IEEE_8087
 #endif
 
 #define __MATH_H__
-#if defined(__APPLE__) && defined(__MACH__) || defined(__FreeBSD__)
+#if defined(__APPLE__) && defined(__MACH__) || defined(__FreeBSD__) || \
+    defined(__OpenBSD__)
 /* stdlib.h on FreeBSD and Apple's 10.5 and later SDKs will mangle the
  * name of strtod.  If it's included after strtod is redefined as
  * gay_strtod, it will mangle the name of gay_strtod, which is