Fix build for OpenBSD

Author: cmburn

src/libblastrampoline.h

@@ -7,6 +7,8 @@ extern "C" {
 // This shamelessly stolen from https://github.com/JuliaLang/julia/blob/master/src/support/platform.h
 #if defined(__FreeBSD__)
 #define _OS_FREEBSD_
+#elif defined(__OpenBSD__)
+#define _OS_OPENBSD_
 #elif defined(__linux__)
 #define _OS_LINUX_
 #elif defined(_WIN32) || defined(_WIN64)

src/libblastrampoline_internal.h

@@ -24,7 +24,7 @@
 #include <dlfcn.h>
 #endif
 
-#ifdef _OS_FREEBSD_
+#if defined(_OS_FREEBSD_) || defined(_OS_OPENBSD_)
 #include <stddef.h>
 #include <sys/sysctl.h>
 #include <dlfcn.h>