patch 8.1.2022: the option.c file is too big

Problem:    The option.c file is too big.
Solution:   Move option definitions to a separate file. (Yegappan Lakshmanan,
            closes #4918)
diff --git a/Filelist b/Filelist
index 1ed1ecd..b40cea6 100644
--- a/Filelist
+++ b/Filelist
@@ -87,6 +87,7 @@
 		src/ops.c \
 		src/option.c \
 		src/option.h \
+		src/optiondefs.h \
 		src/popupmnu.c \
 		src/popupwin.c \
 		src/profiler.c \