Set errno for log1p on pole/domain error.

Set errno for log1p on pole/domain error.

According to bug 6792, errno is not set to ERANGE/EDOM
by calling log1p/log1pf/log1pl with x = -1 or x < -1.

This patch adds a wrapper which sets errno in those cases
and returns the value of the existing __log1p function.
The log1p is now an alias to the wrapper function
instead of __log1p.

The files in sysdeps are reflecting these changes.
The ia64 implementation sets errno by itself,
thus the wrapper-file is empty.

The libm-test is adjusted for log1p-tests to check errno.

	[BZ #6792]
	* math/w_log1p.c: New file.
	* math/w_log1pf.c: Likewise.
	* math/w_log1pl.c: Likewise.
	* math/Makefile (libm-calls): Add w_log1p.
	* math/s_log1pl.c (log1pl): Remove weak_alias.
	* sysdeps/i386/fpu/s_log1p.S (log1p): Likewise.
	* sysdeps/i386/fpu/s_log1pf.S (log1pf): Likewise.
	* sysdeps/i386/fpu/s_log1pl.S (log1pl): Likewise.
	* sysdeps/x86_64/fpu/s_log1pl.S (log1pl): Likewise.
	* sysdeps/ieee754/dbl-64/s_log1p.c (log1p): Likewise.
	[NO_LONG_DOUBLE] (log1pl): Likewise.
	* sysdeps/ieee754/flt-32/s_log1pf.c (log1pf): Likewise.
	* sysdeps/ieee754/ldbl-128/s_log1pl.c (log1pl): Likewise.
	* sysdeps/ieee754/ldbl-64-128/s_log1pl.c
	(log1p): Remove long_double_symbol.
	* sysdeps/ieee754/ldbl-128ibm/s_log1pl.c (log1pl): Likewise.
	* sysdeps/ieee754/ldbl-64-128/w_log1pl.c: New file.
	* sysdeps/ieee754/ldbl-128ibm/w_log1pl.c: Likewise.
	* sysdeps/m68k/m680x0/fpu/s_log1p.c: Define empty weak_alias to
	remove weak_alias for corresponding log1p function.
	* sysdeps/m68k/m680x0/fpu/s_log1pf.c: Likewise.
	* sysdeps/m68k/m680x0/fpu/s_log1pl.c: Likewise.
	* sysdeps/ia64/fpu/w_log1p.c: New file.
	* sysdeps/ia64/fpu/w_log1pf.c: Likewise.
	* sysdeps/ia64/fpu/w_log1pl.c: Likewise.
	* math/libm-test.inc (log1p_test_data):	Add errno expectations.