shells/bash: Revise fix when NLS is off
The fix commited in 17f1bb50e42a45dc64fc898cd9cae905d7262bda clashed
with cc83ec0f744fb159bd48303d15c09aa0c6cb38a4.
The later is a more elegant solution that doesn't require to drop
the header files from being installed.
This commit reverts changes from 17f1bb50e42a45dc64fc898cd9cae905d7262bda.