Fix lexing of zero octal followed by whitespace

We'd call strtol starting at the whitespace, and strtol strips
whitespace...

Fixes oss-fuzz #29272.

Author: nikic

Zend/tests/oct_whitespace.phpt

@@ -0,0 +1,8 @@
+--TEST--
+Octal literal followed by whitespace and another number
+--FILE--
+<?php
+var_dump(0o0 2);
+?>
+--EXPECTF--
+Parse error: syntax error, unexpected integer "2", expecting ")" in %s on line %d

Zend/zend_language_scanner.l

@@ -1963,6 +1963,11 @@ NEWLINE ("\r"|"\n"|"\r\n")
 		--len;
 	}
 
+	if (len == 0) {
+		ZVAL_LONG(zendlval, 0);
+		RETURN_TOKEN_WITH_VAL(T_LNUMBER);
+	}
+
 	if (contains_underscores) {
 		octal = estrndup(octal, len);
 		strip_underscores(octal, &len);