shlwapi: Suppress sign-extension through integer promotion

[Andrew Talbot]

Changelog:
    shlwapi: Suppress sign-extension through integer promotion.

diff --git a/dlls/shlwapi/wsprintf.c b/dlls/shlwapi/wsprintf.c
index 1093393..56eea41 100644
--- a/dlls/shlwapi/wsprintf.c
+++ b/dlls/shlwapi/wsprintf.c
@@ -488,7 +488,7 @@ INT WINAPI wvnsprintfW( LPWSTR buffer, INT maxlen, LPCWSTR spec, __ms_va_list ar
         case WPR_STRING:
             {
                 LPCSTR ptr = argData.lpcstr_view;
-                for (i = 0; i < len; i++) *p++ = (WCHAR)*ptr++;
+                for (i = 0; i < len; i++) *p++ = (BYTE)*ptr++;
             }
             break;
         case WPR_WSTRING:
@@ -514,7 +514,7 @@ INT WINAPI wvnsprintfW( LPWSTR buffer, INT maxlen, LPCWSTR spec, __ms_va_list ar
             /* fall through */
         case WPR_UNSIGNED:
             for (i = len; i < format.precision; i++, maxlen--) *p++ = '0';
-            for (i = sign; i < len; i++) *p++ = (WCHAR)number[i];
+            for (i = sign; i < len; i++) *p++ = (BYTE)number[i];
             break;
         case WPR_UNKNOWN:
             continue;