scripts/libc: do not build add-ons by default

Currently, no --enable-add-ons option is passed to libc configure when
"$(do_libc_add_ons_list ,)" is empty, which makes configure automatically search
for present add-ons. In that case, all present add-ons are built, although
no add-on was selected by the user in the config. Moreover, this can make the
configure fail if some non-standard add-ons like eglibc-localedef are present.

This behavior also leads to an inconsistency from a user point of view between
the following cases:
- LIBC_ADDONS_LIST="", LIBC_GLIBC_USE_PORTS=n and THREADS="none" in the config,
which makes "$(do_libc_add_ons_list ,)" return "", so all present add-ons
are built.
- LIBC_ADDONS_LIST="", LIBC_GLIBC_USE_PORTS=n and THREADS!="none" in the
config, which makes "$(do_libc_add_ons_list ,)" return the add-on supporting
the chosen threading implementation, e.g. "nptl", so only this add-on is
built.

This patch disables the building of all add-ons in that case.

It is still possible to build all present add-ons by adding --enable-add-ons to
LIBC_GLIBC_EXTRA_CONFIG_ARRAY.

Signed-off-by: "Benoît THÉBAUDEAU" <benoit.thebaudeau@advansee.com>

(C) 2007 Yann E. MORIN <yann.morin.1998@anciens.enib.fr>

License: LGPL v2.1

Shut off a stupid warning: preffered-stack-boundary must be between 4 ad 12,

and 2 is not.

diff -dur glibc-2.5.orig/sysdeps/i386/Makefile glibc-2.5/sysdeps/i386/Makefile

--- glibc-2.5.orig/sysdeps/i386/Makefile	2005-03-06 01:18:16.000000000 +0100

+++ glibc-2.5/sysdeps/i386/Makefile	2007-05-27 17:49:37.000000000 +0200

@@ -36,7 +36,7 @@

 ifeq ($(subdir),csu)

 sysdep-CFLAGS += -mpreferred-stack-boundary=4

 else

-sysdep-CFLAGS += -mpreferred-stack-boundary=2

+sysdep-CFLAGS += -mpreferred-stack-boundary=4

 # Likewise, any function which calls user callbacks

 uses-callbacks += -mpreferred-stack-boundary=4

 # Likewise, any stack alignment tests