These changes allow AEL to better check ${} constructs within $[...], that are concatenated with text.

I modified and added rules in ast_expr2.fl to better handle
the concatenations.

I added some default routines to ast_expr2.y so the standalone would
compile. It also looks like I haven't run this thru bison since 2.1, so
it's good to get this updated.

The Makefile has comments added now for check_expr2 and check_expr to
explain what they are for, and how to run them. 

The testexpr2s stuff has been removed, in favor of check_expr2.

expr2.testinput has been updated to include the two expressions
that inspired these changes (from mcnobody on #asterisk this morning)
The regression has been run and all looks well.



git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@179807 65c4cc65-6c06-0410-ace0-fbb531ad65f3

main/ast_expr2.y

@@ -422,6 +422,14 @@ is_zero_or_null (struct val *vp)
 
 #ifdef STANDALONE
 
+void ast_register_file_version(const char *file, const char *version)
+{
+}
+
+void ast_unregister_file_version(const char *file)
+{
+}
+
 void ast_log(int level, const char *file, int line, const char *function, const char *fmt, ...)
 {
 	va_list vars;