tccpp: Fix corner case of fnlike macro invocation

Arg substitution leaves placeholder marker in the stream for
empty arguments.  Those need to be skipped when searching for
a fnlike macro invocation in the replacement list itself.  See
testcase.

tccpp.c

@@ -3023,7 +3023,7 @@ static int next_argstream(Sym **nested_list, int can_read_stream, TokenString *w
         if (macro_ptr) {
             p = macro_ptr, t = *p;
             if (ws_str) {
-                while (is_space(t) || TOK_LINEFEED == t)
+                while (is_space(t) || TOK_LINEFEED == t || TOK_PLCHLDR == t)
                     tok_str_add(ws_str, t), t = *++p;
             }
             if (t == 0 && can_read_stream) {
@@ -3152,7 +3152,9 @@ static int macro_subst_tok(
             } else {
                 tok_str_free_str(ws_str.str);
             }
-            next_nomacro(); /* eat '(' */
+	    do {
+		next_nomacro(); /* eat '(' */
+	    } while (tok == TOK_PLCHLDR);
 
             /* argument macro */
             args = NULL;

tests/pp/18.c

@@ -0,0 +1,15 @@
+#define M_RETI_ARG27(x,y,z,aa, ...)    aa
+#define M_RET_ARG27(...)        M_RETI_ARG27(__VA_ARGS__)
+#define M_COMMA_P(...)          M_RET_ARG27(__VA_ARGS__, 1, 1, 0, useless)
+#define M_EMPTYI_DETECT(...)    0, 1,
+#define M_EMPTYI_P_C1(...)      M_COMMA_P(M_EMPTYI_DETECT __VA_ARGS__ () )
+#define EX
+#define empty(x)
+#define fnlike(x) yeah x
+/* If the following macro is called with empty arg (X183), the use
+   of 'x' between fnlike and '(' doesn't hinder the recognition of this
+   being a further fnlike macro invocation.  */
+#define usefnlike(x) fnlike x (x)
+X181 M_EMPTYI_P_C1()
+X182 M_EMPTYI_P_C1(x)
+X183 usefnlike()

tests/pp/18.expect

@@ -0,0 +1,3 @@
+X181 1
+X182 0
+X183 yeah