Use long endian options for ppc64

Use long endian options for ppc64

GCC options pairs -mlittle/-mlittle-endian and -mbig/-mbig-endian are
equivalent on ppc64 architecture. However, Clang supports only long
version of the options.

Use longer form in configure to properly support both GCC and Clang
compiler. In addition, fix this issue in tcg test configure.

Signed-off-by: Miroslav Rezanina <[email protected]>
Reviewed-by: Greg Kurz <[email protected]>
Message-Id: <20220131091714[email protected]>
Signed-off-by: Cédric Le Goater <[email protected]>