patch 9.1.0957: MS-Windows: conversion warnings

Problem:  MS-Windows: conversion warnings
Solution: add explicit type casts (Yegappan Lakshmanan)

closes: #16288

Signed-off-by: Yegappan Lakshmanan <yegappan@yahoo.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/usercmd.c b/src/usercmd.c
index c0d1bdb..ff2c353 100644
--- a/src/usercmd.c
+++ b/src/usercmd.c
@@ -671,7 +671,7 @@
 	    if (entry != NULL)
 	    {
 		STRCPY(IObuff + len, entry->value.string);
-		len += entry->value.length;
+		len += (int)entry->value.length;
 #ifdef FEAT_EVAL
 		if (p_verbose > 0 && cmd->uc_compl_arg != NULL)
 		{
@@ -681,7 +681,7 @@
 		    {
 			IObuff[len++] = ',';
 			STRCPY(IObuff + len, cmd->uc_compl_arg);
-			len += uc_compl_arglen;
+			len += (int)uc_compl_arglen;
 		    }
 		}
 #endif