Mark internal grp/pwd/shadow functions with attribute_hidden [BZ #18822]
Mark internal grp/pwd/shadow functions with attribute_hidden to allow
direct access within libc.so and libc.a without using GOT nor PLT.
[BZ #18822]
* include/grp.h (__fgetgrent_r): Add attribute_hidden.
(__getgrgid_r): Likewise.
(__getgrnam_r): Likewise.
* include/pwd.h (__getpwuid_r): Likewise.
(__getpwnam_r): Likewise.
(__fgetpwent_r): Likewise.
* include/shadow.h (__getspnam_r): Likewise.
(__sgetspent_r): Likewise.
(__fgetspent_r): Likewise.