pgsql: Hardcode typeof_unqual to __typeof_unqual__ for clang

Hardcode typeof_unqual to __typeof_unqual__ for clang

A new attempt was made in 63275ce84d2 to make typeof_unqual work on all
configurations of CC and CLANG. This re-introduced an old problem
though, where CLANG would only support __typeof_unqual__ but the
configure check for CC detected support for typeof_unqual.

This fixes that by always defining typeof_unqual as __typeof_unqual__
under clang.

Author: Jelte Fennema-Nio <postgres@jeltef.nl>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: /messages/by-id/92f9750f-c7f6-42d8-9a4a-85a3cbe808f3@eisentraut.org

Branch
------
master

Details
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https://git.postgresql.org/pg/commitdiff/2eb6cd327caea42b5f29e0b16d6053c52aa08c3c

Modified Files
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src/include/c.h | 3 +++
1 file changed, 3 insertions(+)