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/DocComment.cpp b/DocComment.cpp
index 2a1c981..02b7ab7 100644
--- a/DocComment.cpp
+++ b/DocComment.cpp
@@ -73,13 +73,13 @@
             break;
     }
 
-    out.setLinePrefix(" *");
+    out.pushLinePrefix(" *");
 
     for (const std::string& line : mLines) {
         out << (line.empty() ? "" : " ") << line << "\n";
     }
 
-    out.unsetLinePrefix();
+    out.popLinePrefix();
     out << " */\n";
 }