Flush warnings file (#8069)

* Flush warnings file

When having a large project the warnings file is buffered but when a long time there are no warnings emitted the last warnings are not yet written.
During testing tis is most obvious when the `dot` process starts and one needs the `.dot` files but not the converted files at hat moment one wants to kill the doxygen process but the result is an incomplete warnings file of the warnings that should already be written.

Created a flush function for the warnings file and placed it at a few strategic points.

* Flush warnings file

Last minute change without proper testing ( :-( )

* Flush warnings file

void is the default changed for consistency and due to (http://www.dietmar-kuehl.de/mirror/c++-faq/newbie.html#faq-29.4):
> C programmers often use f(void) when declaring a function that takes no parameters, however in C++ that is considered bad style. In fact, the f(void) style has been called an "abomination" by Bjarne Stroustrup, the creator of C++, Dennis Ritchie, the co-creator of C, and Doug McIlroy, head of the research department where Unix was born.

1 files changed, 1 insertions, 0 deletions

diff --git a/src/message.h b/src/message.h
index e84344b..dd9eeeb 100644
--- a/src/message.h
+++ b/src/message.h
@@ -35,6 +35,7 @@ extern void err(const char *fmt, ...) PRINTFLIKE(1, 2);
 extern void err_full(const char *file,int line,const char *fmt, ...) PRINTFLIKE(3, 4);
 extern void term(const char *fmt, ...) PRINTFLIKE(1, 2);
 void initWarningFormat();
+void warn_flush();
 
 extern void printlex(int dbg, bool enter, const char *lexName, const char *fileName);