libc/eglibc: fix localedef 2.14 build

The localedef of eglibc 2.14 requires NOT_IN_libc to be defined in order to
compile intl/l10nflist.c.

This is because localedef is built separately from eglibc and uses some parts of
eglibc that don't compile in standalone without this preprocessor definition.

This fixes the following error:

[ALL ] gcc -g -O2 -DNO_SYSCONF -DNO_UNCOMPRESS
-DLOCALE_PATH='"/usr/lib/locale:/usr/share/i18n"'
-DLOCALEDIR='"/usr/lib/locale"' -DLOCALE_ALIAS_PATH='"/usr/share/locale"'
-DCHARMAP_PATH='"/usr/share/i18n/charmaps"'
-DREPERTOIREMAP_PATH='"/usr/share/i18n/repertoiremaps"'
-DLOCSRCDIR='"/usr/share/i18n/locales"' -Iglibc/locale/programs -Iglibc/locale
-I/<snip>/.build/src/eglibc-localedef-2_14/include
-I/<snip>/.build/src/eglibc-localedef-2_14 -I.
-include /<snip>/.build/src/eglibc-localedef-2_14/include/always.h -Wall
-Wno-format -c -o locarchive.o glibc/locale/programs/locarchive.c
[ALL ] glibc/locale/programs/locarchive.c: In function 'enlarge_archive':
[ALL ] glibc/locale/programs/locarchive.c:303:21: warning: variable
'oldlocrectab' set but not used [-Wunused-but-set-variable]
[ALL ] In file included from glibc/locale/programs/locarchive.c:651:0:
[ALL ] glibc/locale/programs/../../intl/l10nflist.c: In function
'_nl_normalize_codeset':
[ERROR] glibc/locale/programs/../../intl/l10nflist.c:342:9: error:
'_nl_C_locobj_ptr' undeclared (first use in this function)
[ALL ] glibc/locale/programs/../../intl/l10nflist.c:342:9: note: each
undeclared identifier is reported only once for each function it appears in
[ALL ] glibc/locale/programs/locarchive.c: In function
'add_locales_to_archive':
[ALL ] glibc/locale/programs/locarchive.c:1450:7: warning: passing argument
1 of '__xpg_basename' discards 'const' qualifier from pointer target type
[enabled by default]
[ALL ] /usr/include/libgen.h:35:14: note: expected 'char *' but argument is
of type 'const char *'
[ERROR] make[1]: *** [locarchive.o] Error 1

Signed-off-by: "Benoît Thébaudeau" <benoit.thebaudeau@advansee.com>
(transplanted from 4cd9134739b594451794cf61a6e1b137422cdafd)

# dmalloc debug facility

## depends on ! BACKEND

##

## help dmalloc helps tracking memory allocation mis-usage

## help such as double-free, use-after-free...

choice

    bool

    prompt "dmalloc version"

# Don't remove next line

# CT_INSERT_VERSION_BELOW

config DMALLOC_V_5_5_2

    bool

    prompt "5.5.2"

endchoice

config DMALLOC_VERSION

    string

# Don't remove next line

# CT_INSERT_VERSION_STRING_BELOW

    default "5.5.2" if DMALLOC_V_5_5_2