Add a test for --as-needed with symbol versioning

	* ld-elf/shared.exp (build_tests): Add libneeded2a.so,
	libneeded2b.so, libneeded2c.o and needed2.

	* ld-elf/needed2.ver: New file.
	* ld-elf/needed2a.c: Likewise.
	* ld-elf/needed2b.c: Likewise.
	* ld-elf/needed2c.c: Likewise.
Remove shared object from -Ttext-segment

	* ld.texinfo: Remove shared object from -Ttext-segment.