Make bits/math-finite.h conditions match other headers (bug 19205).

bits/math-finite.h declares -ffinite-math-only variants of various
functions under conditions not matching those under which the normal
versions are declared.

* math.h only ever includes bits/mathcalls.h to declare float and long
  double functions if __USE_ISOC99, but bits/math-finite.h declares
  some float functions regardless (long double ones are conditioned on
  __MATH_DECLARE_LDOUBLE).  (For C90 functions this isn't a
  conformance bug because C90 reserves the float and long double
  names, but is still contrary to good glibc practice.  For some other
  functions in older XSI standards it *is* a conformance bug.)

* Some functions are defined as inlines using lgamma_r functions under
  conditions where those lgamma_r functions are not themselves
  declared.

* hypot is declared under __USE_XOPEN || __USE_ISOC99 in
  bits/mathcalls.h, __USE_ISOC99 only in bits/math-finite.h.

* float and long double versions of Bessel functions should be limited
  to __USE_MISC (as in bug 18977).

* gamma should not be declared for __USE_XOPEN2K (as in bug 18967).

* remainder should be restricted to __USE_XOPEN_EXTENDED ||
  __USE_ISOC99, not unconditional.

* scalb should not be declared for __USE_XOPEN2K8, and scalbf and
  scalbl are non-POSIX (as in bug 18967).

This patch fixes all these issues (it doesn't seem worth splitting
them into separate patches or bugs).  I put __USE_ISOC99 conditionals,
where needed, around both float and long double declarations, even
though formally redundant around the long double declarations because
__MATH_DECLARE_LDOUBLE isn't defined without __USE_ISOC99; it seemed
clearer that way.  The missing declarations of lgamma_r functions are
dealt with by directly using declarations of __lgamma*_r_finite, in
the implementation namespace, rather than having the inlines rely on
asm redirection of lgamma*_r.

After this patch, there are some apparently redundant nested
__USE_ISOC99 conditionals in lgamma / gamma definitions.  These
actually reflect a separate bug (the correct condition for the lgamma
inline functions to set signgam is __USE_MISC || __USE_XOPEN, the
condition under which signgam is declared, rather than disabling
setting it if __USE_ISOC99, which includes XSI POSIX versions for
which signgam *should* be set).  They'll be fixed as part of a fix for
that bug, which will also add tests for these inlines.  I've put a
note about more general conform/ test coverage for -ffinite-math-only
on
<https://sourceware.org/glibc/wiki/Development_Todo/Master#conformtest_improvements>,
alongside other options for which this is also relevant (some of which
have also had such bugs in the past relating to mismatched
conditionals).

I also intend to enable the main libm-test.inc tests for the
math-finite.h functions, but some other bugs in __*_finite need fixing
first.

	[BZ #19205]
	* math/bits/math-finite.h (acosf): Condition declaration on
	[__USE_ISOC99].
	(acosl): Likewise.
	(acoshf): Likewise.
	(acoshl): Likewise.
	(asinf): Likewise.
	(asinl): Likewise.
	(atan2f): Likewise.
	(atan2l): Likewise.
	(atanhf): Likewise.
	(atanhl): Likewise.
	(coshf): Likewise.
	(coshl): Likewise.
	(expf): Likewise.
	(expl): Likewise.
	(fmodf): Likewise.
	(fmodl): Likewise.
	(hypot): Change condition to [__USE_XOPEN || __USE_ISOC99].
	(j0f): Change condition to [__USE_MISC && __USE_ISOC99].
	(j0l): Likewise.
	(y0f): Likewise.
	(y0l): Likewise.
	(j1f): Likewise.
	(j1l): Likewise.
	(y1f): Likewise.
	(y1l): Likewise.
	(jnf): Likewise.
	(jnl): Likewise.
	(ynf): Likewise.
	(ynl): Likewise.
	(lgammaf_r): Condition declaration on [__USE_ISOC99].
	(lgammal_r): Likewise.
	(__lgamma_r_finite): New declaration.
	(__lgammaf_r_finite): Likewise.
	(__lgammal_r_finite): Likewise.
	(lgamma): Use __lgamma_r_finite.
	(lgammaf): Condition definition on [__USE_ISOC99].  Use
	__lgammaf_r_finite.
	(lgammal): Condition definition on [__USE_ISOC99].  Use
	__lgammal_r_finite.
	(gamma): Do not define for [!__USE_MISC && __USE_XOPEN2K].  Use
	__lgamma_r_finite.
	(gammaf): Condition definition on [__USE_ISOC99].  Use
	__lgammaf_r_finite.
	(gammal): Condition definition on [__USE_ISOC99].  Use
	__lgammal_r_finite.
	(logf): Condition declaration on [__USE_ISOC99].
	(logl): Likewise.
	(log10f): Likewise.
	(log10l): Likewise.
	(ldexpf): Likewise.
	(ldexpl): Likewise.
	(powf): Likewise.
	(powl): Likewise.
	(remainder): Condition declaration on [__USE_XOPEN_EXTENDED ||
	__USE_ISOC99].
	(remainderf): Condition declaration on [__USE_ISOC99].
	(remainderl): Likewise.
	(scalb): Do not declare for [!__USE_MISC && __USE_XOPEN2K8].
	(scalbf): Change condition to [__USE_MISC && __USE_ISOC99].
	(scalbl): Likewise.
	(sinhf): Condition declaration on [__USE_ISOC99].
	(sinhl): Likewise.
	(sqrtf): Likewise.
	(sqrtl): Likewise.

1 files changed, 1 insertions, 1 deletions

diff --git a/NEWS b/NEWS
index 048b94d223..2867ac0dd1 100644
--- a/NEWS
+++ b/NEWS
@@ -22,7 +22,7 @@ Version 2.23
   19003, 19007, 19012, 19016, 19018, 19032, 19046, 19048, 19049, 19050,
   19059, 19071, 19074, 19076, 19077, 19078, 19079, 19085, 19086, 19088,
   19094, 19095, 19124, 19125, 19129, 19134, 19137, 19156, 19174, 19181,
-  19189, 19201.
+  19189, 19201, 19205.
 
 * A defect in the malloc implementation, present since glibc 2.15 (2012) or
   glibc 2.10 via --enable-experimental-malloc (2009), could result in the