linux-user: Bound mmap_min_addr by host page size

Bizzarely, it is possible to set /proc/sys/vm/mmap_min_addr
to a value below the host page size.  Fix that.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Ilya Leoshkevich <iii@linux.ibm.com>
Acked-by: Helge Deller <deller@gmx.de>
Message-Id: <20240102015808.132373-32-richard.henderson@linaro.org>

linux-user/main.c

@@ -901,7 +901,7 @@ int main(int argc, char **argv, char **envp)
         if ((fp = fopen("/proc/sys/vm/mmap_min_addr", "r")) != NULL) {
             unsigned long tmp;
             if (fscanf(fp, "%lu", &tmp) == 1 && tmp != 0) {
-                mmap_min_addr = tmp;
+                mmap_min_addr = MAX(tmp, host_page_size);
                 qemu_log_mask(CPU_LOG_PAGE, "host mmap_min_addr=0x%lx\n",
                               mmap_min_addr);
             }