Recently added typedef "string" is a horrid idea

I see that commit b47b4dbf6 added this to varlena.c:
typedef struct varlena string;

This is a remarkably bad idea.  It will cause pgindent to do strange
things anywhere it sees a variable or field named "string", of which
we have quite a few.  Remember that the effects of typedef names are
*global*, so far as pgindent is concerned; not only varlena.c will
be affected.

Please rename this typedef with some less-generic name.  Probably
some of the other identifiers added in the same commit should be
adjusted to match.
        regards, tom lane