Allow non-root block device mounts when using external fuse.

The internal libfuse has the ability to drop and restore privileges
using setresuid() when ntfs3g is installed with suid root. However, Chrome OS
does not install with suid root, but rather launches ntfs3g as a regular
user with the CAP_SYS_ADMIN capability. This renders the internal libfuse
privilege dropping code ineffective and unnecessary. Because of this, the
safety check to prevent unsafe use of ntfs3g compiled with external libfuse
can be removed, allowing ntfs3g to be compiled with external libfuse.

--- ntfs-3g_ntfsprogs-2017.3.23/src/ntfs-3g.c
+++ ntfs-3g_ntfsprogs-2017.3.23_new/src/ntfs-3g.c
@@ -4174,7 +4174,8 @@
 		ctx->blkdev = TRUE;
 #endif
 
-#ifndef FUSE_INTERNAL
+/* #if FUSE_INTERNAL */
+#if 0
 	if (getuid() && ctx->blkdev) {
 		ntfs_log_error("%s", unpriv_fuseblk_msg);
 		err = NTFS_VOLUME_NO_PRIVILEGE;