* src/su.c: Use a bool when possible instead of int integers.

	* src/su.c: Use a bool when possible instead of int integers.
	* src/su.c: Add brackets and parenthesis.
	* src/su.c: Avoid implicit conversion of pointers / integers
	/ chars to booleans.
	* src/su.c: Ignore the return value of pam_end() before
	exiting.
	* src/su.c: Avoid assignments in comparisons.
	* src/su.c: Avoid multi-statements lines.