GCC 4.7 Solaris updates to install.texi

GCC 4.7 Solaris updates to install.texi

	* doc/install.texi (Specific, i?86-*-solaris2.[89]): Update
	binutils reference.
	(Specific, i?86-*-solaris2.10): Remove GCC 4.0 reference.
	Update binutils references.
	(Specific, *-*-solaris2*): Mention bundled GCC in Solaris 10 and 11.
	Update binutils reference.
	Update Sun as/GNU ld caveat.
	Document binutils largefile requirement for LTO plugin.
	Remove referent to alternate libpthread.

From-SVN: r185242