dwarf2out.c (dwarf2out_begin_prologue): Use crtl->nothrow

dwarf2out.c (dwarf2out_begin_prologue): Use crtl->nothrow

	* dwarf2out.c (dwarf2out_begin_prologue): Use crtl->nothrow
	* tree-eh.c (stmt_could_throw_p): Remove check for WEAK decls.
	* function.h (rtl_data): Add nothrow flag.
	* except.c (set_nothrow_function_flags): Use crtl->nothrow;
	set DECL_NOTHROW for AVAILABLE functions.

From-SVN: r145202