use argv[0] for executable

Index: rts/System/Platform/Misc.h
--- rts/System/Platform/Misc.h.orig
+++ rts/System/Platform/Misc.h
@@ -54,6 +54,11 @@ namespace Platform
 	 */
 	std::string GetProcessExecutablePath();
 
+#ifdef __OpenBSD__
+	const static char *argv0;
+	void SetArgv0(const char *s);
+#endif
+
 	/**
 	 * Returns the path to the module/shared library, including the file name.
 	 * If moduleName is "", the path to the current library is returned.
