pgsql: Fix for new Boolean node

Fix for new Boolean node

The token in nodeTokenType() is actually the whole rest of the string,
so we need to take into account the length to do the correct
comparison.

Without this, postgres_fdw tests fail under
-DWRITE_READ_PARSE_PLAN_TREES.

Branch
------
master

Details
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https://git.postgresql.org/pg/commitdiff/cf925936ecc031355cd56fbd392ec3180517a110

Modified Files
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src/backend/nodes/read.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)