Fix .asciz <expr>... where an overzealous parsing wants to parse too much of the remaining text

In particular, the example was
	.asciz <cr><lf>/<SOH>/
where it tried to make a division betweem <lf> and the delimited
string /<SOH>/.

assemble.c

@@ -1077,7 +1077,7 @@ static int assemble(
                             cp = skipwhite(cp);
                             if (*cp == '<' || *cp == '^') {
                                 /* A byte value */
-                                value = parse_expr(cp, 0);
+                                value = parse_unary_expr(cp, 0);
                                 cp = value->cp;
                                 store_value(stack, tr, 1, value);
                                 free_tree(value);

parse.c

@@ -863,3 +863,26 @@ EX_TREE        *parse_expr(
 
     return value;
 }
+
+/*
+  parse_unary_expr It parses and evaluates
+  an arithmetic expression but only a unary: (op)value or <expr>.
+  In particular, it doesn't try to divide in <lf>/SOH/.
+*/
+
+EX_TREE        *parse_unary_expr(
+    char *cp,
+    int undef)
+{
+    EX_TREE        *expr;
+    EX_TREE        *value;
+
+    expr = parse_unary(cp);            /* Parse into a tree */
+    value = evaluate(expr, undef);     /* Perform the arithmetic */
+    value->cp = expr->cp;              /* Pointer to end of text is part of
+                                          the rootmost node  */
+    free_tree(expr);                   /* Discard parse in favor of
+                                          evaluation */
+
+    return value;
+}

parse.h

@@ -35,6 +35,9 @@ int             get_mode(
 EX_TREE        *parse_expr(
     char *cp,
     int undef);
+EX_TREE        *parse_unary_expr(
+    char *cp,
+    int undef);
 int             parse_float(
     char *cp,
     char **endp,