add operator ^= to mean not equal (like != and <>)

[孙诗浩(思才)]

Hi everyone,
I am doding some jobs in postgres. I want to add "^=" like "!=" and "<>".

So i modify the code in scan.l.
Plan 1:
equals_greater "=>"
less_equals  "<="
greater_equals ">="
less_greater "<>"
not_equals  (!=|\^=)

Maybe i can delete some code to make the code more simple.
Plan 2:
equals_greater "=>"
less_equals  "<="
greater_equals ">="
less_greater "<>" (delete this definition)
not_equals  (!=|\^=|<>)

Before send patch review, I want to konw whether the postgres maintainer will 
approve my changes.

So, please give me some advice.

Thank you!