Change (un)setLinePrefix to push and pop

This allows stacking multiple prefixes together.

Bug: N/A
Test: mma
Test: ./test/run_all_host_tests.sh
Test: ./test/run_all_device_tests.sh
Change-Id: I132c6527ffc4a090ebc4acf3773f3118e50b40ba
diff --git a/generateCppImpl.cpp b/generateCppImpl.cpp
index 278334d..bad6151 100644
--- a/generateCppImpl.cpp
+++ b/generateCppImpl.cpp
@@ -144,7 +144,7 @@
         generateStubImplMethod(out, baseName, method);
     });
 
-    out.setLinePrefix("//");
+    out.pushLinePrefix("//");
     out << iface->definedName() << "* ";
     generateFetchSymbol(out, iface->definedName());
     out << "(const char* /* name */) {\n";
@@ -152,7 +152,7 @@
     out << "return new " << baseName << "();\n";
     out.unindent();
     out << "}\n\n";
-    out.unsetLinePrefix();
+    out.popLinePrefix();
 
     out << "}  // namespace implementation\n";
     enterLeaveNamespace(out, false /* leave */);