pgsql: Reject use of ucol_strcollUTF8() before ICU 53

Reject use of ucol_strcollUTF8() before ICU 53

Various bugs can cause crashes, so don't use that function before ICU
53. It will fall back to the code path used for other encodings.

Since we now tie the function availability to an ICU version, we don't
need the configure test anymore. That also resolves the issue that the
test result was previously hardcoded for Windows.

researched by Daniel Verite <daniel(at)manitou-mail(dot)org>, Peter Geoghegan
<pg(at)bowt(dot)ie>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>

Discussion: https://www.postgresql.org/message-id/flat/f1438ec6-22aa-4029-9a3b-26f79d330e72%40manitou-mail.org

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/d6391b03b3025372620925e5746e65c288a1e371

Modified Files
--------------
configure | 38 --------------------------------------
configure.in | 16 ----------------
src/include/pg_config.h.in | 3 ---
src/include/pg_config.h.win32 | 3 ---
src/include/utils/pg_locale.h | 13 +++++++++++++
5 files changed, 13 insertions(+), 60 deletions(-)