Add constants indicating the maximum values of speed_t and baud_t.
Hopefully if and when the baud_t interface is standardized then
BAUD_MAX will be included in the standardization from the start.

Historically, the __MAX_BAUD symbol has indicated the maximum speed_t
value on at least some platforms (including glibc).  However, this
name would be problematic for future standardization, because it
confusingly implies a reference to baud_t, not speed_t, and it is
inconsistent with other limit symbols, which are all of the form *_MAX
(e.g. SIZE_MAX for size_t.)

[ v3: dropped leading underscores, leave __MAX_BAUD outside
      #ifdef __USE_MISC since it is a legacy symbol, and
      namespace-protected with a double underscore.
      (Collin Funk, Adhermerval Zanella Netto) ]

[ v4: moved from __USE_MISC to __USE_GNU (Collin Funk) ]

Signed-off-by: "H. Peter Anvin" (Intel) <hpa@zytor.com>
Reviewed-by: Collin Funk <collin.funk1@gmail.com>

The generic code has __ispeed and __ospeed; Linux has c_ispeed and
c_ospeed. Use an anonymous union member to allow both set of names on
all platforms.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>

Now all platforms unconditionally use the "sane" definitions of the
termios baud constants. Unify them into a common file.

Note: I have made them explicitly unsigned to avoid problems with
compiler warnings for comparisons of unequal signedness or
similar. These constants were historically octal on most platforms,
and so unsigned by default.

Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>
Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

POSIX requires that speed_t is an unsigned integer type, so change the
generic speed_t definition to be an unsigned int instead of a plain
int.

Reviewed-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>

Implement double and single precision variants of the C23 routine atan2pi
for both AdvSIMD and SVE.

Reviewed-by: Wilco Dijkstra  <Wilco.Dijkstra@arm.com>

Implement double and single precision variants of the C23 routine atanpi
for both AdvSIMD and SVE.

Reviewed-by: Wilco Dijkstra  <Wilco.Dijkstra@arm.com>

Implement double and single precision variants of the C23 routine asinpi
for both AdvSIMD and SVE.

Reviewed-by: Wilco Dijkstra  <Wilco.Dijkstra@arm.com>

Implement double and single precision variants of the C23 routine acospi
for both AdvSIMD and SVE.

Reviewed-by: Wilco Dijkstra  <Wilco.Dijkstra@arm.com>

Vector variant of the new C23 tanpi. New tests pass on AArch64.

Vector variant of the new C23 cospi. New tests pass on AArch64.