c++, tree: declare some basic functions inline

c++, tree: declare some basic functions inline

The functions strip_array_types, is_typedef_decl, typedef_variant_p
and cp_expr_location are used throughout the C++ front end including in
some fairly hot parts (e.g. in the tsubst routines and cp_walk_subtree)
and they're small enough that the overhead of calling them out-of-line
is relatively significant.

So this patch moves their definitions into the appropriate headers to
enable inlining them.

gcc/cp/ChangeLog:

	* cp-tree.h (cp_expr_location): Define here.
	* tree.cc (cp_expr_location): Don't define here.

gcc/ChangeLog:

	* tree.cc (strip_array_types): Don't define here.
	(is_typedef_decl): Don't define here.
	(typedef_variant_p): Don't define here.
	* tree.h (strip_array_types): Define here.
	(is_typedef_decl): Define here.
	(typedef_variant_p): Define here.