Use const char * for static insline string const in llava_runner.h (#12840)

With std::string, its constructor is part of dynamic initialization and
across TUs the order is undefined, so code in another static initializer
might see it before it’s constructed

Author: shoumikhin

examples/models/llava/runner/llava_runner.h

@@ -63,7 +63,7 @@ class ET_EXPERIMENTAL LlavaRunner
       bool echo = true) override;
 
  private:
-  inline static const std::string kPresetPrompt =
+  inline static const char* kPresetPrompt =
       "A chat between a curious human and an artificial intelligence assistant. The assistant gives helpful, detailed, and polite answers to the human's questions. USER: ";
 };