Register LLVM SPIR-V Backend as SPIR-V generator (KhronosGroup#423)

* Register LLVM SPIR-V Backend as SPIR-V generator

* Change LLVM SPIR-V Backend vendor from "Intel" to "LLVM"

Author: michalpaszkowski

include/spirv/spir-v.xml

@@ -93,7 +93,8 @@
         <id value="40"  vendor="NVIDIA" tool="Slang Compiler" comment="Contact Theresa Foley, [email protected], https://github.com/shader-slang/slang/"/>
         <id value="41"  vendor="Zig Software Foundation" tool="Zig Compiler" comment="Contact Robin Voetter, https://github.com/Snektron"/>
         <id value="42"  vendor="Rendong Liang" tool="spq" comment="Contact Rendong Liang, [email protected], https://github.com/PENGUINLIONG/spq-rs"/>
-        <unused start="43" end="0xFFFF" comment="Tool ID range reservable for future use by vendors"/>
+        <id value="43"  vendor="LLVM" tool="LLVM SPIR-V Backend" comment="Contact Michal Paszkowski, [email protected], https://github.com/llvm/llvm-project/tree/main/llvm/lib/Target/SPIRV"/>
+        <unused start="44" end="0xFFFF" comment="Tool ID range reservable for future use by vendors"/>
     </ids>
 
     <!-- SECTION: SPIR-V Opcodes and Enumerants -->