Update cpp/ql/src/experimental/Security/CWE/CWE-266/IncorrectPrivilegeAssignment.cpp

Co-authored-by: Geoffrey White <40627776+geoffw0@users.noreply.github.com>

Author: ihsinme

cpp/ql/src/experimental/Security/CWE/CWE-266/IncorrectPrivilegeAssignment.cpp

@@ -4,7 +4,7 @@
   maskOut = S_IRWXG | S_IRWXO;
   umask(maskOut); // GOOD
   ...
-  fchmod(fileno(fp), 0555 - cmusk); // BAD 
+  fchmod(fileno(fp), 0555 - maskOut); // BAD 
   ...
   fchmod(fileno(fp), 0555 & ~maskOut); // GOOD
 ...