re PR tree-optimization/51737 (g++ crashes (internal compiler error: Segmentation fault) when compiling quickbook)

	PR middle-end/51737
	* cgraph.c (cgraph_remove_node_and_inline_clones): Add FORBIDDEN_NODE
	parameter.
	* cgraph.h (cgraph_remove_node_and_inline_clones): Update prototype.
	* ipa-inline-transform.c (save_inline_function_body): Remove copied clone
	if needed.
	* tree-inline.c (delete_unreachable_blocks_update_callgraph): Update.

	PR middle-end/51737
	* g++.dg/torture/pr51737.C: New testcase

From-SVN: r185694