Revert "glibc: install the obsolete libnsl"

Revert "glibc: install the obsolete libnsl"

libnsl from Glibc is deprecated and should not be used anymore.
Remove libnsl.so.* from GLIBC_LIBS_LIB.

libnsl is now an separate library that can be packaged later if
necessary [1].

Note: libnsl from Glibc doesn't build with gcc 8 due new warning [2].

[1] https://github.com/thkukuk/libnsl.git
[2] http://patchwork.sourceware.org/patch/26437

This reverts commit 398747f5fafca8c07e696612d8eded53d4f935c7.

Signed-off-by: Romain Naour <romain.naour@gmail.com>
Cc: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>