Use gimple_call for callgraph edges

Use gimple_call for callgraph edges

This corresponds to:
  [PATCH 55/89] Use gimple_call for callgraph edges
  https://gcc.gnu.org/ml/gcc-patches/2014-04/msg01221.html
from the original 89-patch kit

That earlier patch was approved by Jeff:
> OK once prereqs go in.
in https://gcc.gnu.org/ml/gcc-patches/2014-05/msg00867.html

gcc/
	* cgraph.h (cgraph_edge::call_stmt): Strengthen field from plain
	gimple to a gimple_call.
	(cgraph_node::set_call_stmt_including_clones): Likewise for param
	"new_stmt".
	(cgraph_node::create_edge): Likewise for param "call_stmt".
	(cgraph_node::create_indirect_edge): Likewise.
	(cgraph_node::create_edge_including_clones): Likewise for param
	"stmt".
	(cgraph_edge::set_call_stmt): Likewise for param "new_stmt".
	(cgraph_edge::clone): Likewise for param "call_stmt".
	(symbol_table::create_edge): Likewise.

	* cgraph.c (cgraph_edge::set_call_stmt): Require a gimple_call
	rather than a plain gimple.
	(symbol_table::create_edge): Likewise.
	(cgraph_node::create_edge): Likewise.
	(cgraph_node::create_indirect_edge): Likewise.
	(cgraph_edge::redirect_call_stmt_to_callee): Strengthen local
	"new_stmt" from gimple to gimple_call.
	(cgraph_update_edges_for_call_stmt_node): Add checked casts to
	gimple_call.

	* cgraphbuild.c (pass_build_cgraph_edges::execute): Replace
	is_gimple_call with dyn_cast<gimple_call> and new local
	"call_stmt".
	(cgraph_edge::rebuild_edges): Likewise.

	* cgraphclones.c (cgraph_edge::clone): Require a gimple_call
	rather than a plain gimple.
	(cgraph_node::set_call_stmt_including_clones): Likewise.
	(cgraph_node::create_edge_including_clones): Likewise.

	* lto-streamer-in.c (fixup_call_stmt_edges_1): Add checked casts
	to gimple_call.

	* omp-low.c (simd_clone_adjust): Strengthen local "call" from
	gimple to gimple_call.

	* trans-mem.c (ipa_tm_insert_irr_call): Likewise for "g".
	(ipa_tm_insert_gettmclone_call): Likewise; also strengthen "g2"
	to gimple_assign.

	* tree-emutls.c (gen_emutls_addr): Strengthen local "x" from
	gimple to gimple_call.

	* tree-inline.c (copy_bb): Replace is_gimple_call with
	dyn_cast<gimple_call> and new local "call_stmt".

	* value-prof.c (gimple_ic): Require and return a gimple_call,
	rather than a plain gimple.
	* value-prof.h (gimple_ic): Likewise.