Vulkan: include backend name in deviceName

* Add rr::BackendName() to dynamically return the name of the backend
* Set VkPhysicalDeviceProperties::deviceName to include backend name

Bug: b/130459196
Change-Id: I028f3607e4eda9de55bc4cec8af78e7b4793160d
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/39552
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>
Tested-by: Antonio Maiorano <amaiorano@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>

src/Reactor/LLVMReactor.cpp

diff --git a/src/Reactor/LLVMReactor.cpp b/src/Reactor/LLVMReactor.cpp
index 7b06cb4..70ada9c 100644
--- a/src/Reactor/LLVMReactor.cpp
+++ b/src/Reactor/LLVMReactor.cpp
@@ -1000,6 +1000,11 @@
 
 namespace rr {
 
+std::string BackendName()
+{
+	return std::string("LLVM ") + LLVM_VERSION_STRING;
+}
+
 const Capabilities Caps = {
 	true,  // CoroutinesSupported
 };