FreeBSD: Fix bootstrapping tools under Linux/musl

musl libc has deprecated LFS64 aliases, so bootstrapping FreeBSD tools
under musl distros has been failing with stat64 errors.

Apply the aliases under non-glibc Linux to fix this problem.

Reviewed-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Val Packett <val@packett.cool>
Closes openzfs#15780

lib/libspl/include/os/freebsd/sys/stat.h

@@ -76,8 +76,12 @@ fstat64_blk(int fd, struct stat64 *st)
 /*
  * Only Intel-based Macs have a separate stat64; Arm-based Macs are like
  * FreeBSD and have a full 64-bit stat from the start.
+ *
+ * On Linux, musl libc is full 64-bit too and has deprecated its own version
+ * of these defines since version 1.2.4.
  */
-#if defined(__APPLE__) && !(defined(__i386__) || defined(__x86_64__))
+#if (defined(__APPLE__) && !(defined(__i386__) || defined(__x86_64__))) || \
+	(defined(__linux__) && !defined(__GLIBC__))
 #define	stat64	stat
 #define	fstat64	fstat
 #endif