patch 8.2.1975: Win32: memory leak when encoding conversion fails

Problem:    Win32: memory leak when encoding conversion fails.
Solution:   Free the allocated memory. (Ken Takata, closes #7277)

src/os_win32.c

@@ -3532,7 +3532,10 @@ mch_get_acl(char_u *fname)
 
 	wn = enc_to_utf16(fname, NULL);
 	if (wn == NULL)
+	{
+	    vim_free(p);
 	    return NULL;
+	}
 
 	// Try to retrieve the entire security descriptor.
 	err = GetNamedSecurityInfoW(

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1975,
 /**/
     1974,
 /**/