re PR c/6300 (sparc-sun-solaris2.7 gcc-3.1 C testsuite failure in gcc.dg/cpp/charconst.c)

re PR c/6300 (sparc-sun-solaris2.7 gcc-3.1 C testsuite failure in gcc.dg/cpp/charconst.c)

	* c-lex.c (lex_charconst): Call convert to get constant in
	proper type; don't just smash the type field.
	Fixes PR c/6300.

	* config.gcc: Add list of obsolete configurations.  Disallow
	building these without --enable-obsolete.
	* doc/install.texi: Document --enable-obsolete and obsoletion
	policy.  Mention obsoletion of individual targets in
	appropriate places.

From-SVN: r52639