Retry commits of file writes for up to a second to work around AV scanning

Poorly-written antivirus software briefly lock newly written files to
scan them for viruses, which makes the rename from the temp file to
actual file fail. Work around this by retrying the rename up to ten
times.

Closes #1618.

aegisub/libaegisub/common/io.cpp

@@ -97,7 +97,22 @@ Save::Save(const std::string& file, bool binary)
 
 Save::~Save() {
 	delete fp;
+#ifndef _WIN32
 	util::Rename(tmp_name, file_name);
+#else
+	for (int i = 0; i < 10; ++i) {
+		try {
+			util::Rename(tmp_name, file_name);
+			return;
+		}
+		catch (agi::FileNotAccessibleError const&) {
+			// Retry up to ten times in case it's just locked by a poorly-written antivirus scanner
+			if (i == 9)
+				throw;
+			Sleep(100);
+		}
+	}
+#endif
 }
 
 std::ofstream& Save::Get() {