Do not "fixify" the content of extra compiler input variables twice

MakefileGenerator::initOutPaths should only do that: init out paths.
It's not supposed to modify the content of input variables for extra
compilers. Those get "fixed" in MakefileGenerator::init below the "do
the path fixifying" comment.

The first "fixifying" would turn an absolute path in SOURCES (input
variable for the moc_source extra compiler) into a path relative to
the output directory. The second "fixifying" would mess everything up.

Fixes: QTBUG-76097
Change-Id: I8c50ef33d097dba4a1db76144c70b0677beffb6c
Reviewed-by: Kai Koehne <kai.koehne@qt.io>

qmake/generators/makefile.cpp

@@ -199,7 +199,6 @@ MakefileGenerator::initOutPaths()
             ProStringList &inputs = project->values((*it2).toKey());
             for (ProStringList::Iterator input = inputs.begin(); input != inputs.end(); ++input) {
                 QString finp = fileFixify((*input).toQString(), FileFixifyFromOutdir);
-                *input = ProString(finp);
                 QString path = replaceExtraCompilerVariables(tmp_out, finp, QString(), NoShell);
                 path = Option::normalizePath(path);
                 int slash = path.lastIndexOf('/');