[lldb/Plugins] Use external functions to (de)initialize plugins

This is a step towards making the initialize and terminate calls be
generated by CMake, which in turn is towards making it possible to
disable plugins at configuration time.

Differential revision: https://reviews.llvm.org/D74245

lldb/source/Plugins/LanguageRuntime/RenderScript/RenderScriptRuntime/RenderScriptRuntime.cpp

@@ -46,6 +46,8 @@ using namespace lldb;
 using namespace lldb_private;
 using namespace lldb_renderscript;
 
+LLDB_PLUGIN(RenderScriptRuntime);
+
 #define FMT_COORD "(%" PRIu32 ", %" PRIu32 ", %" PRIu32 ")"
 
 char RenderScriptRuntime::ID = 0;