pgsql: Add macro to disable address safety instrumentation

Add macro to disable address safety instrumentation

fasthash_accum_cstring_aligned() uses a technique, found in various
strlen() implementations, to detect a string's NUL terminator by
reading a word at at time. That triggers failures when testing with
"-fsanitize=address", at least with frontend code. To enable using
this function anywhere, add a function attribute macro to disable
such testing.

Reviewed by Jeff Davis

Discussion: https://postgr.es/m/CANWCAZbwvp7oUEkbw-xP4L0_S_WNKq-J-ucP4RCNDPJnrakUPw%40mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/db17594ad73a871a176a9bf96e0589c2cf57052c

Modified Files
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src/include/c.h                      | 13 +++++++++++++
src/include/common/hashfn_unstable.h |  5 ++++-
2 files changed, 17 insertions(+), 1 deletion(-)