gccrs: trivial typo fix.

gccrs: trivial typo fix.

Fix subsititions -> substitutions

gcc/rust/ChangeLog:

	* backend/rust-compile-base.cc (HIRCompileBase::compile_function):
	Fix typo in substitutions.
	(HIRCompileBase::resolve_method_address): Likewise.
	* backend/rust-compile-extern.h (CompileExternItem::visit):
	Likewise.
	* backend/rust-compile-implitem.cc (CompileTraitItem::visit):
	Likewise.
	* backend/rust-compile-intrinsic.cc (maybe_override_ctx):
	Likewise.
	* backend/rust-compile-item.cc (CompileItem::visit): Likewise.
	* backend/rust-compile-resolve-path.cc
	(HIRCompileBase::query_compile): Likewise.
	* typecheck/rust-coercion.cc (TypeCoercionRules::do_coercion):
	Likewise.
	* typecheck/rust-hir-type-check-item.cc
	(TypeCheckItem::ResolveImplBlockSelfWithInference): Likewise.
	* typecheck/rust-hir-type-check-path.cc (TypeCheckExpr::visit):
	Likewise.
	* typecheck/rust-hir-type-check-type.cc (TypeCheckType::visit):
	Likewise.
	* typecheck/rust-tyty.cc (BaseType::has_subsititions_defined):
	Renamed into ...
	(BaseType::has_substitutions_defined): ... this.
	(ADTType::is_equal): Fix typo in substitutions.
	(handle_substitions): Likewise.
	(FnType::is_equal): Likewise.
	(FnType::handle_substitions): Likewise.
	* typecheck/rust-tyty.h (has_subsititions_defined): Renamed into
	...
	(has_substitutions_defined): ... this.

Signed-off-by: Marc Poulhiès <dkm@kataplop.net>