pgsql: Avoid possible crash within libsanitizer.

Avoid possible crash within libsanitizer.

We've successfully used libsanitizer for awhile with the undefined
and alignment sanitizers, but with some other sanitizers (at least
thread and hwaddress) it crashes due to internal recursion before
it's fully initialized itself.  It turns out that that's due to the
"__ubsan_default_options" hack installed by commit f686ae82f, and we
can fix it by ensuring that __ubsan_default_options is built without
any sanitizer instrumentation hooks.

Reported-by: Emmanuel Sibi <emmanuelsibi.mec@gmail.com>
Reported-by: Alexander Lakhin <exclusion@gmail.com>
Diagnosed-by: Emmanuel Sibi <emmanuelsibi.mec@gmail.com>
Fix-suggested-by: Jacob Champion <jacob.champion@enterprisedb.com>
Author: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/F7543B04-E56C-4D68-A040-B14CCBAD38F1@gmail.com
Discussion: https://postgr.es/m/dbf77bf7-6e54-ed8a-c4ae-d196eeb664ce@gmail.com
Backpatch-through: 16

Branch
------
REL_16_STABLE

Details
-------
https://git.postgresql.org/pg/commitdiff/c775bf048abdb625d862c94f945c2fa11ccf0907

Modified Files
--------------
src/backend/main/main.c | 17 +++++++++++++----
1 file changed, 13 insertions(+), 4 deletions(-)