patch 7.4.918
Problem:    A digit in an option name has problems.
Solution:   Rename 'python3dll' to 'pythonthreedll'.
diff --git a/src/option.h b/src/option.h
index 739fd67..f872836 100644
--- a/src/option.h
+++ b/src/option.h
@@ -689,7 +689,7 @@
 EXTERN char_u	*p_perldll;	/* 'perldll' */
 #endif
 #if defined(DYNAMIC_PYTHON3) && !defined(WIN3264)
-EXTERN char_u	*p_py3dll;	/* 'python3dll' */
+EXTERN char_u	*p_py3dll;	/* 'pythonthreedll' */
 #endif
 #if defined(DYNAMIC_PYTHON) && !defined(WIN3264)
 EXTERN char_u	*p_pydll;	/* 'pythondll' */