Fix expansion of multibyte character after $1 - $9, $?, etc (#102)

A multibyte character immediately following an expansion of a
single-character name, e.g. $1 through $9, $?, $-, etc. was
corrupted when in a UTF-8 locale, e.g.:

    $ set -- foo; echo "$1テスト"
    foo?スト

Prior discussion:
https://www.mail-archive.com/ast-users@lists.research.att.com/msg01060.html
https://bugzilla.redhat.com/show_bug.cgi?id=1256495

src/cmd/ksh93/sh/macro.c:
- Apply a Red Hat patch by Paulo Andrade that avoids calling
  fcmbget() if backtracking more than one byte might be required.

src/cmd/ksh93/tests/basic.c:
- Test "テスト" following expansion of "$1", "$?" and "$#".

Co-authored-by: Martijn Dekker <martijn@inlv.org>

src/cmd/ksh93/sh/macro.c

@@ -1506,7 +1506,10 @@ retry1:
 	    default:
 		goto nosub;
 	}
-	c = fcmbget(&LEN);
+	if(type)
+		c = fcmbget(&LEN);
+	else
+		c = fcget();
 	if(type>M_TREE)
 	{
 		if(c!=RBRACE)