enhancement: try to detect files with different capitalization in ext…

…ensions (#1611)

When opening files with zfile, try to check for different capitalization cases in the file extension.
Hopefully this should cover incorrect filenames in CD images, where the .CUE file refers to one filename but what actually exists has a different capitalization (e.g. mp3 vs MP3)

src/zfile.cpp

@@ -1986,6 +1986,26 @@ static struct zfile *zfile_fopenx2 (const TCHAR *name, const TCHAR *mode, int ma
 		if (f)
 			return f;
 	}
+#ifdef AMIBERRY
+	// capitalize file extension then try again
+	TCHAR *ext = _tcsrchr(tmp, '.');
+	if (ext) {
+		for (TCHAR *p = ext; *p; ++p) {
+			*p = _totupper(*p);
+		}
+		f = zfile_fopen_x(tmp, mode, mask, index);
+		if (f)
+			return f;
+
+		// try again with lowercase extension
+		for (TCHAR *p = ext; *p; ++p) {
+			*p = _totlower(*p);
+		}
+		f = zfile_fopen_x(tmp, mode, mask, index);
+		if (f)
+			return f;
+	}
+#endif
 #if 0
 	name += 2;
 	if (name[0] == '/' || name[0] == '\\')