Gracefully handle bad octal literals

The code handling integer literals in dtc-lexer.l assumes that the flex
regexp means that strtoull() can't fail to interpret the string as a valid
integer (either decimal, octal, or hexadecimal).  This is not true for
octals.  For example '09' is accepted as a literal by the regexp,
strtoull() attempts to handle it as octal, but it has a bad digit.

This changes the code to give a more useful error in this case.

Reported-by: Anton Blanchard <anton@samba.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
diff --git a/dtc-lexer.l b/dtc-lexer.l
index 0ee1caf..22dda7d 100644
--- a/dtc-lexer.l
+++ b/dtc-lexer.l
@@ -153,7 +153,10 @@
 			errno = 0;
 			yylval.integer = strtoull(yytext, &e, 0);
 
-			assert(!(*e) || !e[strspn(e, "UL")]);
+			if (*e && e[strspn(e, "UL")]) {
+				lexical_error("Bad integer literal '%s'",
+					      yytext);
+			}
 
 			if (errno == ERANGE)
 				lexical_error("Integer literal '%s' out of range",