Add llogb, llogbf, llogbl.

TS 18661-1 defines llogb functions that are like ilogb except that
they return long int instead of int.  Corresponding FP_LLOGB* macros
are defined, whose values are required to have the obvious
correspondence to those of the FP_ILOGB* macros.

This patch implements these functions and macros for glibc.  llogb
uses the type-generic infrastructure, with an implementation similar
to the wrapper for ilogb but with additional conversion from FP_ILOGB*
to FP_LLOGB*; this approach avoids needing to modify or duplicate any
of the architecture-specific ilogb implementations.  Tests are also
based on those for ilogb.

Ideally the llogb functions would alias the ilogb ones when long is
32-bit, but such aliasing requires the associated header declarations
of the different-type alias to be hidden, typically by defining macros
before including the header (see e.g. how
sysdeps/ieee754/dbl-64/wordsize-64/s_llround.c defines lround to
__hidden_lround before including <math.h>).  The infrastructure for
type-generic function implementations does not support defining such
macros at present (since C code can't define a macro whose name is
determined by other macros).  So this patch leaves them as separate
functions (similar to e.g. scalbln and scalbn being separate in such a
case as well), but with the remapping of FP_ILOGB* to FP_LLOGB*
conditioned out in the case where it would be the identity map.

Tested for x86_64, x86, mips64 and powerpc.

	* math/bits/mathcalls.h [__GLIBC_USE (IEC_60559_BFP_EXT)] (llogb):
	New declaration.
	* math/tgmath.h [__GLIBC_USE (IEC_60559_BFP_EXT)] (llogb): New
	macro.
	* math/math.h [__GLIBC_USE (IEC_60559_BFP_EXT)] (__FP_LONG_MAX):
	New macro.
	[__GLIBC_USE (IEC_60559_BFP_EXT)] (FP_LLOGB0): Likewise.
	[__GLIBC_USE (IEC_60559_BFP_EXT)] (FP_LLOGBNAN): Likewise.
	* math/Versions (llogb): New libm symbol at version GLIBC_2.25.
	(llogbf): Likewise.
	(llogbl): Likewise.
	* math/Makefile (gen-libm-calls): Add w_llogbF.
	(tests): Add test-fp-llogb-constants.
	* math/w_llogb_template.c: New file.  Based on
	math/w_ilogb_template.c.
	* math/libm-test.inc (llogb_test_data): New array.
	(llogb_test): New function.
	(main): Call llogb_test.
	* math/test-fp-llogb-constants.c: New file.  Based on
	math/test-fp-ilogb-constants.c.
	* math/test-tgmath-ret.c (llogb): New CHECK_RET_CONST call.
	(do_test): Call check_return_llogb.
	* math/test-tgmath.c (NCALLS): Increase to 126.
	(F(compile_test)): Call llogb.
	(F(llogb)): New function.
	* manual/math.texi (Exponents and Logarithms): Document llogb,
	llogbf, llogbl, FP_LLOGB0 and FP_LLOGBNAN.
	* manual/libm-err-tab.pl (@all_functions): Add llogb.
	* sysdeps/ieee754/ldbl-opt/nldbl-llogb.c: New file.
	* sysdeps/ieee754/ldbl-opt/w_llogbl.c: Likewise.
	* sysdeps/ieee754/ldbl-opt/Makefile (libnldbl-calls): Add llogb.
	(CFLAGS-nldbl-llogb.c): New variable.
	* sysdeps/nacl/libm.abilist: Update.
	* sysdeps/unix/sysv/linux/aarch64/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/alpha/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/arm/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/hppa/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/i386/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/ia64/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/m68k/coldfire/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/m68k/m680x0/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/microblaze/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/mips/mips32/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/mips/mips64/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/nios2/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libm.abilist:
	Likewise.
	* sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libm.abilist:
	Likewise.
	* sysdeps/unix/sysv/linux/powerpc/powerpc64/libm-le.abilist:
	Likewise.
	* sysdeps/unix/sysv/linux/powerpc/powerpc64/libm.abilist:
	Likewise.
	* sysdeps/unix/sysv/linux/s390/s390-32/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/s390/s390-64/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/sh/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/sparc/sparc32/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/sparc/sparc64/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/tile/tilegx/tilegx32/libm.abilist:
	Likewise.
	* sysdeps/unix/sysv/linux/tile/tilegx/tilegx64/libm.abilist:
	Likewise.
	* sysdeps/unix/sysv/linux/tile/tilepro/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/x86_64/64/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/x86_64/x32/libm.abilist: Likewise.

math/math.h

@@ -97,11 +97,13 @@ typedef _Float128x double_t;
 # endif
 #endif
 
-/* Define macros for the return value of ilogb, based on
+/* Define macros for the return values of ilogb and llogb, based on
    __FP_LOGB0_IS_MIN and __FP_LOGBNAN_IS_MIN.
 
     FP_ILOGB0	Expands to a value returned by `ilogb (0.0)'.
     FP_ILOGBNAN	Expands to a value returned by `ilogb (NAN)'.
+    FP_LLOGB0	Expands to a value returned by `llogb (0.0)'.
+    FP_LLOGBNAN	Expands to a value returned by `llogb (NAN)'.
 
 */
 
@@ -118,6 +120,23 @@ typedef _Float128x double_t;
 #  define FP_ILOGBNAN	2147483647
 # endif
 #endif
+#if __GLIBC_USE (IEC_60559_BFP_EXT)
+# if __WORDSIZE == 32
+#  define __FP_LONG_MAX 0x7fffffffL
+# else
+#  define __FP_LONG_MAX 0x7fffffffffffffffL
+# endif
+# if __FP_LOGB0_IS_MIN
+#  define FP_LLOGB0	(-__FP_LONG_MAX - 1)
+# else
+#  define FP_LLOGB0	(-__FP_LONG_MAX)
+# endif
+# if __FP_LOGBNAN_IS_MIN
+#  define FP_LLOGBNAN	(-__FP_LONG_MAX - 1)
+# else
+#  define FP_LLOGBNAN	__FP_LONG_MAX
+# endif
+#endif
 
 /* Get information about long double.  */