REThreaded: convert gen- and delete-Textures to no-ops

Bug: 199501005
Test: make
Test: perfetto trace

These functions are not implemented by SkiaGLRenderEngine, so blocking
on them does not serve any purpose. Skip them unless we're running the
THREADED (implicitly GLES) version.

In a local perfetto trace, this reduces the time for these methods from
around 100 microseconds to around 1 microsecond.

Change-Id: I86945d5a1e565db423c181bc828c3f168301784b
diff --git a/libs/renderengine/threaded/RenderEngineThreaded.cpp b/libs/renderengine/threaded/RenderEngineThreaded.cpp
index 3d446e8..08fc814 100644
--- a/libs/renderengine/threaded/RenderEngineThreaded.cpp
+++ b/libs/renderengine/threaded/RenderEngineThreaded.cpp
@@ -178,6 +178,10 @@
 
 void RenderEngineThreaded::genTextures(size_t count, uint32_t* names) {
     ATRACE_CALL();
+    // This is a no-op in SkiaRenderEngine.
+    if (getRenderEngineType() != RenderEngineType::THREADED) {
+        return;
+    }
     std::promise<void> resultPromise;
     std::future<void> resultFuture = resultPromise.get_future();
     {
@@ -194,6 +198,10 @@
 
 void RenderEngineThreaded::deleteTextures(size_t count, uint32_t const* names) {
     ATRACE_CALL();
+    // This is a no-op in SkiaRenderEngine.
+    if (getRenderEngineType() != RenderEngineType::THREADED) {
+        return;
+    }
     std::promise<void> resultPromise;
     std::future<void> resultFuture = resultPromise.get_future();
     {