configure: Remove tcg/ from the preprocessor include search list

configure: Remove tcg/ from the preprocessor include search list

All tcg includes are relative to the repository root directory,
we can safely remove the tcg/ directory from the include search
path list.

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Stefan Weil <sw@weilnetz.de>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20200101112303.20724-5-philmd@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>