Add new macro IN_MODULE to identify module in which source is built

The current scheme to identify which module a translation unit is
built in depends on defining multiple macros IS_IN_* and also defining
NOT_IN_libc if we're building a non-libc module.  In addition, there
is an IN_LIB macro that does effectively the same thing, but for
different modules (notably the systemtap probes).  This macro scheme
unifies both ideas to use just one macro IN_MODULE and assign it a
value depending on the module it is being built into.  If the module
is not defined, it defaults to MODULE_libc.

Patches that follow will replace uses of IS_IN_* variables with the
IS_IN() macro.  libc-symbols.h has been converted already to give an
example of how such a transition will look.

Verified that there are no relevant binary changes.  One source change
that will crop up repeatedly is that of nscd_stat, since it uses the
build timestamp as a constant in its logic.

	* Makeconfig (in-module): Get value of libof set for the
	translation unit.
	(CPPFLAGS): Use $(in-module).
	* Makerules: Don't suffix routine names for nonlib.
	* include/libc-modules.h: New file.
	* include/libc-symbols.h: Include libc-modules.h
	(IS_IN): New macro to replace IS_IN_* macros.
	* elf/Makefile: Set libof-* for each routine.
	* elf/rtld-Rules: Likewise.
	* extra-modules.mk: Likewise.
	* iconv/Makefile: Likewise.
	* iconvdata/Makefile: Likewise.
	* locale/Makefile: Likewise.
	* malloc/Makefile: Likewise.
	* nss/Makefile: Likewise.
	* sysdeps/gnu/Makefile: Likewise.
	* sysdeps/ieee754/ldbl-opt/Makefile: Likewise.
	* sysdeps/unix/sysv/linux/Makefile: Likewise.
	* sysdeps/s390/s390-64/Makefile: Likewise.
	* nscd/Makefile: Set libof-* for each routine.  Set CFLAGS and
	CPPFLAGS for nscd instead of nonlib.
Fix -Wundef warning in SHLIB_COMPAT

Replace the IS_IN_##lib with IS_IN(lib).  Verified that the generated
code remains the same.

	* include/shlib-compat.h (_SHLIB_COMPAT): Use IS_IN.
Auto-generate libc-modules.h

Remove libc-modules.h from the tree and auto-generate it from
soversions.i and the list of modules in the built-modules variable
defined in Makeconfig.  Macros generated have increasing numbered
values, with built-modules having lower values starting from 1,
following which a separator value LIBS_BEGIN is added and then finally
the library names from soversions.i are appended to the list.  This
allows us to conveniently differentiate between the versioned
libraries and other built modules, which is needed in errno.h and
netdb.h to decide whether to use an internal symbol or an external
one.

Verified that generated code remains unchanged on x86_64.

	* Makeconfig (built-modules): List non-library modules to be
	built.
	(module-cppflags): Include libc-modules.h for
	everything except shlib-versions.v.i.
	(CPPFLAGS): Use it.
	(before-compile): Add libc-modules.h.
	($(common-objpfx)libc-modules.h,
	$(common-objpfx)libc-modules.stmp): New targets.
	(common-generated): Add libc-modules.h and libc-modules.stmp.
	($(common-objpfx)Versions.v.i): Depend on libc-modules.h.
	* include/libc-symbols.h: Don't include libc-modules.h.
	* include/libc-modules.h: Remove file.
	* scripts/gen-libc-modules.awk: New script to generate
	libc-modules.h.
	* sysdeps/unix/Makefile ($(common-objpfx)sysd-syscalls):
	Depend on libc-modules.stmp.
CVE-2014-7817: wordexp fails to honour WRDE_NOCMD.

The function wordexp() fails to properly handle the WRDE_NOCMD
flag when processing arithmetic inputs in the form of "$((... ``))"
where "..." can be anything valid. The backticks in the arithmetic
epxression are evaluated by in a shell even if WRDE_NOCMD forbade
command substitution. This allows an attacker to attempt to pass
dangerous commands via constructs of the above form, and bypass
the WRDE_NOCMD flag. This patch fixes this by checking for WRDE_NOCMD
in exec_comm(), the only place that can execute a shell. All other
checks for WRDE_NOCMD are superfluous and removed.

We expand the testsuite and add 3 new regression tests of roughly
the same form but with a couple of nested levels.

On top of the 3 new tests we add fork validation to the WRDE_NOCMD
testing. If any forks are detected during the execution of a wordexp()
call with WRDE_NOCMD, the test is marked as failed. This is slightly
heuristic since vfork might be used in the future, but it provides a
higher level of assurance that no shells were executed as part of
command substitution with WRDE_NOCMD in effect. In addition it doesn't
require libpthread or libdl, instead we use the public implementation
namespace function __register_atfork (already part of the public ABI
for libpthread).

Tested on x86_64 with no regressions.
Test that pthread_create diagnoses invalid scheduling parameters.
NPTL: Don't (re)validate sched_priority in pthread_create.