i386: Fix C99 compatibility issues in the x86-64 AVX ABI test suite

i386: Fix C99 compatibility issues in the x86-64 AVX ABI test suite

gcc/testsuite/

	* gcc.target/x86_64/abi/avx/avx-check.h (main): Call
	__builtin_printf instead of printf.
	* gcc.target/x86_64/abi/avx/test_passing_m256.c
	(fun_check_passing_m256_8_values): Add missing void return
	type.
	* gcc.target/x86_64/abi/avx512f/avx512f-check.h (main): Call
	__builtin_printf instead of printf.
	* gcc.target/x86_64/abi/avx512f/test_passing_m512.c
	(fun_check_passing_m512_8_values): Add missing void return
	type.
	* gcc.target/x86_64/abi/bf16/bf16-check.h (main): Call
	__builtin_printf instead of printf.
	* gcc.target/x86_64/abi/bf16/m256bf16/bf16-ymm-check.h (main):
	Likewise.
	* gcc.target/x86_64/abi/bf16/m256bf16/test_passing_m256.c
	(fun_check_passing_m256bf16_8_values): Add missing void
	return type.
	* gcc.target/x86_64/abi/bf16/m512bf16/bf16-zmm-check.h (main):
	Call __builtin_printf instead of printf.
	* gcc.target/x86_64/abi/bf16/m512bf16/test_passing_m512.c
	(fun_check_passing_m512bf16_8_values): Add missign void
	return type.