Avoid compat symbols for totalorder in powerpc64le IEEE long double

Avoid compat symbols for totalorder in powerpc64le IEEE long double

No changes since v3.

No changes since v2.

Changes since v1:

  - Added comment on the redefinition of libm_alias_float128_other_r_ldbl.

-- 8< --
On powerpc64le, the libm_alias_float128_other_r_ldbl macro is
used to create an alias between totalorderf128 and __totalorderlieee128,
as well as between the totalordermagf128 and __totalordermaglieee128.

However, the totalorder* and totalordermag* functions changed their
parameter type since commit ID 42760d764649 and got compat symbols for
their old versions.  With this change, the aforementioned macro would
create two conflicting aliases for __totalorderlieee128 and
__totalordermaglieee128.

This patch avoids the creation of the alias between the IEEE long double
symbols (__totalorderl*ieee128) and the compat symbols, because the IEEE
long double functions have never been exported thus don't need such
compat symbol.

Tested for powerpc64le.

Reviewed-by: Joseph Myers <joseph@codesourcery.com>