testsuite part 1 for _BitInt support [PR102989]

testsuite part 1 for _BitInt support [PR102989]

This patch adds first part of the testsuite support.  When creating the
testcases, I've been using
https://defuse.ca/big-number-calculator.htm
tool, a randombitint tool I wrote (posted as a reply to the first series) plus
LLVM trunk on godbolt and the WIP GCC support checking if both compilers
agree on stuff (and in case of differences tried constant evaluation etc.).
The whole testsuite has been also tested with
make -j32 -k check-gcc GCC_TEST_RUN_EXPENSIVE=1 \
RUNTESTFLAGS='GCC_TEST_RUN_EXPENSIVE=1 --target_board=unix\{-m32,-m64\} ubsan.exp=bitint*.c dg.exp=bitint* dg-torture.exp=bitint*'
to verify it in all modes, normally I'm limitting the torture tests to just
-O0 and -O2 because they are quite large and expensive.
Generally it is needed to test different _BitInt precisions because they
are lowered differently (the small vs. medium vs. large vs. huge, precision
of multiples of limb precision or some other etc.).

2023-09-06  Jakub Jelinek  <jakub@redhat.com>

	PR c/102989
gcc/testsuite/
	* lib/target-supports.exp (check_effective_target_bitint,
	check_effective_target_bitint128, check_effective_target_bitint575):
	New effective targets.
	* gcc.dg/bitint-1.c: New test.
	* gcc.dg/bitint-2.c: New test.
	* gcc.dg/bitint-3.c: New test.
	* gcc.dg/bitint-4.c: New test.
	* gcc.dg/bitint-5.c: New test.
	* gcc.dg/bitint-6.c: New test.
	* gcc.dg/bitint-7.c: New test.
	* gcc.dg/bitint-8.c: New test.
	* gcc.dg/bitint-9.c: New test.
	* gcc.dg/bitint-10.c: New test.
	* gcc.dg/bitint-11.c: New test.
	* gcc.dg/bitint-12.c: New test.
	* gcc.dg/bitint-13.c: New test.
	* gcc.dg/bitint-14.c: New test.
	* gcc.dg/bitint-15.c: New test.
	* gcc.dg/bitint-16.c: New test.
	* gcc.dg/bitint-17.c: New test.
	* gcc.dg/bitint-18.c: New test.
	* gcc.dg/torture/bitint-1.c: New test.
	* gcc.dg/torture/bitint-2.c: New test.
	* gcc.dg/torture/bitint-3.c: New test.
	* gcc.dg/torture/bitint-4.c: New test.
	* gcc.dg/torture/bitint-5.c: New test.
	* gcc.dg/torture/bitint-6.c: New test.
	* gcc.dg/torture/bitint-7.c: New test.
	* gcc.dg/torture/bitint-8.c: New test.
	* gcc.dg/torture/bitint-9.c: New test.
	* gcc.dg/torture/bitint-10.c: New test.
	* gcc.dg/torture/bitint-11.c: New test.
	* gcc.dg/torture/bitint-12.c: New test.
	* gcc.dg/torture/bitint-13.c: New test.
	* gcc.dg/torture/bitint-14.c: New test.
	* gcc.dg/torture/bitint-15.c: New test.
	* gcc.dg/torture/bitint-16.c: New test.
	* gcc.dg/torture/bitint-17.c: New test.
	* gcc.dg/torture/bitint-18.c: New test.
	* gcc.dg/torture/bitint-19.c: New test.