gccrs: Implement default HIR visitor class

gcc/rust/ChangeLog:

	* Make-lang.in: Scaffolding new rust-hir-visitor files
	* hir/tree/rust-hir-visitor.h (DefaultHIRVisitor): Declare default HIR visitor
	* hir/tree/rust-hir-visitor.cc  (DefaultHIRVisitor): Define default HIR visitor

Signed-off-by: Ryutaro Okada <[email protected]>

Author: sakupan102

gcc/rust/Make-lang.in

@@ -81,6 +81,7 @@ GRS_OBJS = \
     rust/rust-ast-dump.o \
     rust/rust-ast-collector.o \
     rust/rust-ast-visitor.o \
+    rust/rust-hir-visitor.o \
     rust/rust-hir-dump.o \
     rust/rust-session-manager.o \
     rust/rust-compile.o \