AVX512FP16: Add testcase for vector init and broadcast intrinsics.
gcc/testsuite/ChangeLog:
* gcc.target/i386/m512-check.h: Add union128h, union256h, union512h.
* gcc.target/i386/avx512fp16-10a.c: New test.
* gcc.target/i386/avx512fp16-10b.c: Ditto.
* gcc.target/i386/avx512fp16-1a.c: Ditto.
* gcc.target/i386/avx512fp16-1b.c: Ditto.
* gcc.target/i386/avx512fp16-1c.c: Ditto.
* gcc.target/i386/avx512fp16-1d.c: Ditto.
* gcc.target/i386/avx512fp16-1e.c: Ditto.
* gcc.target/i386/avx512fp16-2a.c: Ditto.
* gcc.target/i386/avx512fp16-2b.c: Ditto.
* gcc.target/i386/avx512fp16-2c.c: Ditto.
* gcc.target/i386/avx512fp16-3a.c: Ditto.
* gcc.target/i386/avx512fp16-3b.c: Ditto.
* gcc.target/i386/avx512fp16-3c.c: Ditto.
* gcc.target/i386/avx512fp16-4.c: Ditto.
* gcc.target/i386/avx512fp16-5.c: Ditto.
* gcc.target/i386/avx512fp16-6.c: Ditto.
* gcc.target/i386/avx512fp16-7.c: Ditto.
* gcc.target/i386/avx512fp16-8.c: Ditto.
* gcc.target/i386/avx512fp16-9a.c: Ditto.
* gcc.target/i386/avx512fp16-9b.c: Ditto.
* gcc.target/i386/pr54855-13.c: Ditto.
* gcc.target/i386/avx512fp16-vec_set_var.c: Ditto.