patch 8.2.5069: various warnings from clang on MS-Windows

Problem:    Various warnings from clang on MS-Windows.
Solution:   Fix the code to avoid the warnings. (Yegappan Lakshmanan,
            closes #10538)
diff --git a/src/os_mswin.c b/src/os_mswin.c
index 6310a1a..b6e8d71 100644
--- a/src/os_mswin.c
+++ b/src/os_mswin.c
@@ -560,7 +560,7 @@
 	    && idx < (int)rb->AppExecLinkReparseBuffer.StringCount
 	    && idx != 2; )
     {
-	if ((*p++ == L'\0'))
+	if (*p++ == L'\0')
 	    ++idx;
     }