hurd: Disable Prefer_MAP_32BIT_EXEC on non-x86_64 for now

While we could support it on any architecture, the tunable is currently
only defined on x86_64.

Signed-off-by: Sergey Bugaev <bugaevc@gmail.com>
Message-ID: <20240323173301.151066-5-bugaevc@gmail.com>

sysdeps/mach/hurd/dl-sysdep.c

@@ -457,7 +457,7 @@ __mmap (void *addr, size_t len, int prot, int flags, int fd, off_t offset)
   if (prot & PROT_EXEC)
     vmprot |= VM_PROT_EXECUTE;
 
-#ifdef __LP64__
+#ifdef __x86_64__
   if ((addr == NULL) && (prot & PROT_EXEC)
       && HAS_ARCH_FEATURE (Prefer_MAP_32BIT_EXEC))
     flags |= MAP_32BIT;

sysdeps/mach/hurd/mmap.c

@@ -60,7 +60,7 @@ __mmap (void *addr, size_t len, int prot, int flags, int fd, off_t offset)
   copy = ! (flags & MAP_SHARED);
   anywhere = ! (flags & MAP_FIXED);
 
-#ifdef __LP64__
+#ifdef __x86_64__
   if ((addr == NULL) && (prot & PROT_EXEC)
       && HAS_ARCH_FEATURE (Prefer_MAP_32BIT_EXEC))
     flags |= MAP_32BIT;