Rename PERFETTO_EXPORT to PERFETTO_COMPONENT_EXPORT

We already have different export macros, and a future CL is going to
introduce a different one.

This rename tries to make it clearer that the PERFETTO_EXPORT macro is
only used for component builds.

Change-Id: Iad322496afb4560f42f81dbb5662a48cd384dd91
diff --git a/src/protozero/protoc_plugin/cppgen_plugin.cc b/src/protozero/protoc_plugin/cppgen_plugin.cc
index 164fb63..fdc6821 100644
--- a/src/protozero/protoc_plugin/cppgen_plugin.cc
+++ b/src/protozero/protoc_plugin/cppgen_plugin.cc
@@ -532,7 +532,8 @@
 void CppObjGenerator::GenClassDecl(const Descriptor* msg, Printer* p) const {
   std::string full_name = GetFullName(msg);
   p->Print(
-      "\nclass PERFETTO_EXPORT $n$ : public ::protozero::CppMessageObj {\n",
+      "\nclass PERFETTO_COMPONENT_EXPORT $n$ : public "
+      "::protozero::CppMessageObj {\n",
       "n", full_name);
   p->Print(" public:\n");
   p->Indent();