Small fixes for mingw building

src/CMakeLists.txt

@@ -17,9 +17,13 @@ add_subdirectory (xoj-preview-extractor)
 
 # Used for both util and xournalpp targets
 set (CMAKE_CXX_FLAGS
-  "${CMAKE_CXX_FLAGS} -g -rdynamic -Wreturn-type -Wuninitialized -Wunused-value -Wunused-variable"
+  "${CMAKE_CXX_FLAGS} -g -Wreturn-type -Wuninitialized -Wunused-value -Wunused-variable"
 )
 
+if (NOT WIN32)
+  set (CMAKE_CXX_FLAGS -rdynamic)
+endif ()
+
 option (DEBUG_COMPILE "Pass -Wall to CXX_FLAGS" OFF)
 mark_as_advanced (FORCE DEBUG_COMPILE)
 

src/util/OutputStream.cpp

@@ -27,7 +27,11 @@ GzOutputStream::GzOutputStream(path filename)
 
 	this->fp = NULL;
 	this->filename = filename;
+#ifdef _WIN32
+	this->fp = gzopen_w(filename.c_str(), "w");
+#else
 	this->fp = gzopen(filename.c_str(), "w");
+#endif
 	if (this->fp == NULL)
 	{
 		this->error = (bl::format("error opening file: \"{1}\"") % filename.string()).str();