pgsql: Fix lcov duplicate directory specification in non-VPATH builds.

Fix lcov duplicate directory specification in non-VPATH builds.

In an in-tree build, "make coverage-html" invoked lcov with two
"-d ." options, because $(srcdir) is just ".". With lcov 2.0
(and perhaps earlier versions?) that results in scanning every
foo.gcda file twice and producing counts twice what they should
be. With later lcov versions (at least 2.3), it results in
"duplicate file" errors.

In VPATH builds we do need two -d options to cover both regular
and generated .c files. But in in-tree builds it suffices to
specify "-d .", so suppress the second switch.

Author: Narek Galstyan <narek(dot)galstyan(at)enterprisedb(dot)com>
Reviewed-by: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Discussion: https://postgr.es/m/CAHsn6_xCDQWe8_vVFhtFk27_xTdyVV+Dr0yWzaooBZ6+-VH-5w@mail.gmail.com
Backpatch-through: 14

Branch
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REL_15_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/e299fc2b30f9f58691aa0782f6bc3ae3fd9f1f52

Modified Files
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src/Makefile.global.in | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)