WEFAX mingw32 fixes

* Fixed mingw32 build issues caused by
    recent WEFAX additions.

src/misc/stacktrace.cxx

@@ -54,12 +54,14 @@ static void pstack(ostream& out, unsigned skip = 0);
 
 void diediedie(void)
 {
+#ifndef __MINGW32__
 	// If this environment variable is set, creates a core dump.
 	if( getenv("FLDIGI_COREDUMP") )
 	{
 		signal(SIGSEGV, SIG_DFL);
 		kill(getpid(), SIGSEGV);
 	}
+#endif
 
 	static bool print_trace = true;
 

src/misc/strutil.cxx

@@ -70,15 +70,21 @@ vector<string> split(const char* re_str, const char* str, unsigned max_split)
 /// Builds a string out of a printf-style formatted vararg list.
 string strformat( const char * fmt, ... )
 {
-	struct auto_free // Automatically deleted when leaving.
-	{
-		char * _strp ;
-		~auto_free() { if( _strp ) free( _strp ); }
-	} ptr = { NULL };
+	static const int sz_buf = 512 ;
+	char buf_usual[sz_buf];
+ 
+ 	va_list ap;
+	va_start(ap, fmt);
+	int res = vsnprintf( buf_usual, sz_buf, fmt, ap);
+	va_end(ap);
+ 	if( res < 0 ) throw runtime_error(__FUNCTION__);
+	if( res < sz_buf ) return buf_usual ;
 
-	va_list ap;
-	va_start  (ap, fmt);
-	int res = vasprintf( &ptr._strp, fmt, ap);
+	string str( res, ' ' );
+	va_start(ap, fmt);
+	res = vsnprintf( &str[0], res + 1, fmt, ap);
+	va_end(ap);
 	if( res < 0 ) throw runtime_error(__FUNCTION__);
-	return ptr._strp ? string( ptr._strp, res ) : string();
+	return str ;
 }
+

src/widgets/picture.cxx

@@ -46,6 +46,7 @@
 #include <FL/Fl.H>
 #include <FL/fl_draw.H>
 
+#include <zlib.h>
 #include <png.h>
 
 #include "fl_digi.h"