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>

diff -durN gcc-3.4.6.orig/gcc/config/sh/lib1funcs.asm gcc-3.4.6/gcc/config/sh/lib1funcs.asm

--- gcc-3.4.6.orig/gcc/config/sh/lib1funcs.asm	2003-08-12 03:25:07.000000000 +0200

+++ gcc-3.4.6/gcc/config/sh/lib1funcs.asm	2007-08-15 23:04:26.000000000 +0200

@@ -37,9 +37,19 @@

    ELF local label prefixes by J"orn Rennecke

    amylaar@cygnus.com  */

+#define ALIAS(X,Y)	.global GLOBAL(X); .set GLOBAL(X),GLOBAL(Y)

+

 #ifdef __ELF__

 #define LOCAL(X)	.L_##X

-#define FUNC(X)		.type X,@function

+

+#if 1 /* ??? The export list mechanism is broken, everything that is not

+	 hidden is exported.  */

+#undef FUNC

+#define FUNC(X)		.type X,@function; .hidden X

+#undef ALIAS

+#define ALIAS(X,Y)	.global GLOBAL(X); .set GLOBAL(X),GLOBAL(Y); .hidden GLOBAL(X)

+#endif

+

 #define ENDFUNC0(X)	.Lfe_##X: .size X,.Lfe_##X-X

 #define ENDFUNC(X)	ENDFUNC0(X)

 #else