hidl-gen -Lc++-impl: Fix inconsistent space for namespace closure.

Test: hidl-gen -Lc++-impl -randroid.hardware:hardware/interfaces
android.hardware.tests.foo@1.0 -o ~/tmp
then manually looked at ~/tmp/Foo.cpp

Bug: 33280246
Change-Id: Id27e28dcd98fadf19a8410b0ba48a8317f792725
diff --git a/generateCppImpl.cpp b/generateCppImpl.cpp
index e9cd776..cb3487b 100644
--- a/generateCppImpl.cpp
+++ b/generateCppImpl.cpp
@@ -243,7 +243,7 @@
     out.unindent();
     out << "}\n\n";
 
-    out << "} // namespace implementation\n";
+    out << "}  // namespace implementation\n";
     enterLeaveNamespace(out, false /* leave */);
 
     return OK;