pgsql: More precise errors from initial pg_control check

More precise errors from initial pg_control check

Use a separate error message for invalid checkpoint location and
invalid state instead of just "invalid data" for both.

Reviewed-by: Michael Paquier <michael@paquier.xyz>
Discussion: https://www.postgresql.org/message-id/20191107041630.GK1768@paquier.xyz

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/b85e43feb3e837699239aba6b8e0f280a59417be

Modified Files
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src/backend/access/transam/xlog.c | 82 +++++++++++++++++++++++----------------
1 file changed, 48 insertions(+), 34 deletions(-)