Fix #581 (Failure when header is included twice with different macros defined)

[danmar]

There was a regression introduced by #468 . This PR just reverts the #468 changes and introduces a test.

[danmar]

@firewave This is a critical bug for me and I can't release Cppcheck with this bug.

So when this fix is merged I want to make a new simplecpp tag and merge it to cppcheck.. you made many refactorings since 1.6.1 do you think we should tag HEAD or make a release branch that only contains this change..

[firewave]

CC @glankk

[glankk]

Caused by nextcond not being set in if tokens with a false condition when followed by an elif. A fix:

diff --git a/simplecpp.cpp b/simplecpp.cpp
index 7d306fd..ef891eb 100644
--- a/simplecpp.cpp
+++ b/simplecpp.cpp
@@ -3701,12 +3701,11 @@ void simplecpp::preprocess(simplecpp::TokenList &output, const simplecpp::TokenL
                     else
                         ifstates.push(conditionIsTrue ? True : ElseIsTrue);
                     iftokens.push(rawtok);
-                } else if (ifstates.top() == True) {
-                    ifstates.top() = AlwaysFalse;
-                    iftokens.top()->nextcond = rawtok;
-                    iftokens.top() = rawtok;
-                } else if (ifstates.top() == ElseIsTrue && conditionIsTrue) {
-                    ifstates.top() = True;
+                } else {
+                    if (ifstates.top() == True)
+                        ifstates.top() = AlwaysFalse;
+                    else if (ifstates.top() == ElseIsTrue && conditionIsTrue)
+                        ifstates.top() = True;
                     iftokens.top()->nextcond = rawtok;
                     iftokens.top() = rawtok;
                 }