Inline __ieee754__rem_pio2(). With gcc4-2, this gives an average

Inline __ieee754__rem_pio2().  With gcc4-2, this gives an average
optimization of about 10% for cos(x), sin(x) and tan(x) on
|x| < 2**19*pi/2.  We didn't do this before because __ieee754__rem_pio2()
is too large and complicated for gcc-3.3 to inline very well.  We don't
do this for float precision because it interferes with optimization
of the usual (?) case (|x| < 9pi/4) which is manually inlined for float
precision only.

This has some rough edges:
- some static data is duplicated unnecessarily.  There isn't much after
  the recent move of large tables to k_rem_pio2.c, and some static data
  is duplicated to good affect (all the data static const, so that the
  compiler can evaluate expressions like 2*pio2 at compile time and
  generate even more static data for the constant for this).
- extern inline is used (for the same reason as in previous inlining of
  k_cosf.c etc.), but C99 apparently doesn't allow extern inline
  functions with static data, and gcc will eventually warn about this.

Convert to __FBSDID().

Indent __ieee754_rem_pio2()'s declaration consistently (its style was
made inconsistent with fdlibm a while ago, so complete this).

Fix __ieee754_rem_pio2()'s return type to match its prototype.  Someone
changed too many ints to int32_t's when fixing the assumption that all
ints are int32_t's.