Fix build on NetBSD

[moubctez]

Version 1.3.2 fails to build on NetBSD:

ld: libmysofa.a(reader.c.o): in function `getArray':
reader.c:(.text+0x6c): undefined reference to `letoh64'

This patch is needed to fix the issue:

--- src/hrtf/portable_endian.h.orig	2023-10-15 19:23:14.526442578 +0000
+++ src/hrtf/portable_endian.h
@@ -41,11 +41,11 @@
 #	define __LITTLE_ENDIAN LITTLE_ENDIAN
 #	define __PDP_ENDIAN    PDP_ENDIAN
 
-#elif defined(__OpenBSD__)
+#elif defined(__NetBSD__) || defined(__OpenBSD__)
 
 #	include <sys/endian.h>
 
-#elif defined(__NetBSD__) || defined(__FreeBSD__) || defined(__DragonFly__)
+#elif defined(__FreeBSD__) || defined(__DragonFly__)
 
 #	include <sys/endian.h>