Update IncorrectPrivilegeAssignment.cpp

Author: ihsinme

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

@@ -1,7 +1,8 @@
 ...
   umask(0); // BAD
 ...
-  cmusk = umask(S_IRWXG | S_IRWXO); // GOOD
+  maskOut = S_IRWXG | S_IRWXO;
+  umask(maskOut); // GOOD
   ...
   fchmod(fileno(fp), 0555 - cmusk); // BAD 
   ...