firejail.txt: remove extraneous endif

Added on commit b689b69 ("make --private-lib a compile time option,
disabled by default", 2023-03-09).

Relates to #5727.

Author: kmk3

src/man/firejail.txt

@@ -698,7 +698,6 @@ Print all recognized protocols in the current Firejail software build and exit.
 Example:
 .br
 $ firejail \-\-debug-protocols
-#endif
 .TP
 \fB\-\-debug-syscalls
 Print all recognized system calls in the current Firejail software build and exit.