Remove support for demangling GCC 2.x era mangling schemes.

Remove support for demangling GCC 2.x era mangling schemes.

libiberty/
	* cplus-dem.c: Remove cplus_mangle_opname, cplus_demangle_opname,
	internal_cplus_demangle, and all subroutines.
	(libiberty_demanglers): Remove entries for ancient GNU (pre-3.0),
	Lucid, ARM, HP, and EDG demangling styles.
	(cplus_demangle): Remove 'work' variable.  Don't call
	internal_cplus_demangle.
include/
	* demangle.h: Remove support for ancient GNU (pre-3.0), Lucid,
	ARM, HP, and EDG demangling styles.

From-SVN: r267363