Mark internal getXXXbyYYY functions with attribute_hidden [BZ #18822]

Mark internal getXXXbyYYY functions with attribute_hidden [BZ #18822]

Mark internal getXXXbyYYY functions with attribute_hidden to allow direct
access within libc.so and libc.a without using GOT nor PLT.

	[BZ #18822]
	* include/aliases.h (__getaliasbyname_r): Add attribute_hidden.
	* include/netdb.h (__gethostbyaddr_r): Likewise.
	(__gethostbyname_r): Likewise.
	(__gethostbyname2_r): Likewise.
	(__getnetbyaddr_r): Likewise.
	(__getnetbyname_r): Likewise.
	(__getservbyname_r): Likewise.
	(__getservbyport_r): Likewise.
	(__getprotobyname_r): Likewise.
	(__getprotobynumber_r): Likewise.
	(__getnetgrent_r): Likewise.
	* include/rpc/netdb.h (__getrpcbyname_r): Likewise.
	(__getrpcbynumber_r): Likewise.
	* nss/getXXbyYY.c (INTERNAL (REENTRANT_NAME)): Likewise.