package/libglib2: fix NLS build on musl and uclibc

package/libglib2: fix NLS build on musl and uclibc

libglib2 uses a very crude and error-prone way to detect the intl
functions, which basically fails when the C library is not glibc.

There is a bug report about this in upstream meson [1], but it doesn't
seem to get any progress. Fixing that properly in Buildroot looks
complicated.

Now that a meson package can specify its LDFLAGS, use that to pass the
infrastructure-provided TARGET_NLS_LIBS to link with.

Fixes:
    http://autobuild.buildroot.org/results/f0d/f0d85d76786343d767fba9c7c5c01f042ecfc018/
    [...]

[1] https://github.com/mesonbuild/meson/issues/3740

Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
Cc: Adam Duskett <aduskett@gmail.com>
Cc: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>