pgsql: Further -Wimplicit-fallthrough cleanup.

Further -Wimplicit-fallthrough cleanup.

Tom's earlier commit in 41c912cad159 didn't update a few cases that
are only encountered with the non-standard --with-llvm config
flag. Additionally there's also one case that appears to be a
deficiency in gcc's (up to trunk as of a few days ago) detection of
"fallthrough" comments - changing the placement slightly fixes that.

Author: Andres Freund
Discussion: /messages/by-id/20180502003239.wfnqu7ekz7j7imm4@alap3.anarazel.de

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/2993435dbae5deb8d2f6c2a715690a5aef4eddb8

Modified Files
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src/backend/jit/llvm/llvmjit_expr.c | 11 +++++------
src/interfaces/libpq/fe-secure.c | 3 ++-
2 files changed, 7 insertions(+), 7 deletions(-)