[Blockable] Shorten LOGD message

We commonly use foo=0x1234 in log messages in EMPER.

emper/Blockable.hpp

@@ -71,7 +71,7 @@ class Blockable : public Logger<logSubsystem> {
 		// Only contexts managed by EMPER's runtime can block.
 		emper::assertInRuntime();
 
-		LOGD("block() blockedContext is " << Context::getCurrentContext());
+		LOGD("block() blockedContext=" << Context::getCurrentContext());
 
 		maybeSetAffinity();