equix: Add NetBSD to "huge pages not supported" path

As suggested by @wiz on #40843, let's add an explicit check to
hashx_vm_alloc_huge() that avoids using a Linux-style default
on NetBSD targets.

This doesn't change the questionable Linux-style default,
but a future patch will disable this code by default so it's not a
portability liability.

(This code is in hashx's VM layer but it's actually only relevant to
equix.)

This addresses bug #40843. Another patch will disable huge pages
by default entirely, but this patch is sufficient to fix the NetBSD
build.

src/ext/equix/hashx/src/virtual_memory.c

@@ -106,8 +106,8 @@ void* hashx_vm_alloc_huge(size_t bytes) {
 #elif defined(__FreeBSD__)
 	mem = mmap(NULL, bytes, PAGE_READWRITE, MAP_PRIVATE | MAP_ANONYMOUS
 		| MAP_ALIGNED_SUPER, -1, 0);
-#elif defined(__OpenBSD__)
-	mem = MAP_FAILED; // OpenBSD does not support huge pages
+#elif defined(__OpenBSD__) || defined(__NetBSD__)
+	mem = MAP_FAILED; // OpenBSD and NetBSD do not support huge pages
 #else
 	mem = mmap(NULL, bytes, PAGE_READWRITE, MAP_PRIVATE | MAP_ANONYMOUS
 		| MAP_HUGETLB | MAP_POPULATE, -1, 0);