Change parser template implementation file ext

We have a few more template implementation files within the rust frontend
that use the hxx extension to make their content clear and highlight the
missing header guards.

gcc/rust/ChangeLog:

	* parse/rust-parse-impl-lexer.cc: Fix included file name.
	* parse/rust-parse-impl-macro.cc: Likewise.
	* parse/rust-parse-impl-proc-macro.cc: Likewise.
	* parse/rust-parse-impl.h: Move to...
	* parse/rust-parse-impl.hxx: ...here.

Signed-off-by: Pierre-Emmanuel Patry <pierre-emmanuel.patry@embecosm.com>

Author: P-E-P

gcc/rust/parse/rust-parse-impl-lexer.cc

@@ -16,7 +16,7 @@
 // along with GCC; see the file COPYING3.  If not see
 // <http://www.gnu.org/licenses/>.
 
-#include "rust-parse-impl.h"
+#include "rust-parse-impl.hxx"
 
 namespace Rust {
 

gcc/rust/parse/rust-parse-impl-macro.cc

@@ -16,7 +16,7 @@
 // along with GCC; see the file COPYING3.  If not see
 // <http://www.gnu.org/licenses/>.
 
-#include "rust-parse-impl.h"
+#include "rust-parse-impl.hxx"
 #include "rust-macro-invoc-lexer.h"
 
 namespace Rust {

gcc/rust/parse/rust-parse-impl-proc-macro.cc

@@ -16,7 +16,7 @@
 // along with GCC; see the file COPYING3.  If not see
 // <http://www.gnu.org/licenses/>.
 
-#include "rust-parse-impl.h"
+#include "rust-parse-impl.hxx"
 #include "rust-proc-macro-invoc-lexer.h"
 
 namespace Rust {