Fix powerpc-nofpu __fe_enabled_env and __fe_nonieee_env (bug 17261).

Fix powerpc-nofpu __fe_enabled_env and __fe_nonieee_env (bug 17261).

On powerpc, floating-point environment macros are defined as pointers
to constants in the library that contain the bit-patterns of the
desired environment, instead of being magic constants cast to pointer
type.

For soft-float, the bit-patterns used for fenv_t are not laid out the
same as for hard-float.  (e500 has a third layout used; that's not an
ABI issue because these values are only meaningful within a single
process, all of whose glibc libraries must come from the same build of
glibc.)  While the __fe_dfl_env value for soft-float was appropriate
for the soft-float fenv_t representation, the other two constants had
the same bit-patterns as for hard-float.  Those bit patterns had the
effect of having exceptions already raised, causing
math/test-fenv-return to fail; this patch fixes the patterns used.
(__fe_nonieee_env also had exceptions unmasked, though they should be
masked to match hard-float semantics.  Since there is no separate
non-IEEE mode for soft-float, it's most appropriate for
__fe_nonieee_env to be the same as __fe_dfl_env; this patch makes it
an alias.)

Tested for powerpc-nofpu.

	[BZ #17261]
	* sysdeps/powerpc/nofpu/fenv_const.c (__fe_enabled_env): Change
	value to 0.
	(__fe_nonieee_env): Define as an alias for __fe_dfl_env.