options.texi (Variable, Var, Init): Update documentation without reference to VarExists.

options.texi (Variable, Var, Init): Update documentation without reference to VarExists.

	* doc/options.texi (Variable, Var, Init): Update documentation
	without reference to VarExists.
	(VarExists): Remove.
	* common.opt, config/i386/i386.opt, config/linux.opt,
	config/rs6000/rs6000.opt, config/sh/sh.opt, config/spu/spu.opt:
	Don't use VarExists.

c-family:
	* c.opt: Don't use VarExists.

fortran:
	* lang.opt: Don't use VarExists.

java:
	* lang.opt: Don't use VarExists.

From-SVN: r164724