Shuffling spirv code so it's not tied to xe::gpu.

Will make it easier to use in standalone apps.

src/xenia/gpu/premake5.lua

@@ -8,8 +8,10 @@ project("xenia-gpu")
   language("C++")
   links({
     "elemental-forms",
+    "spirv-tools",
     "xenia-base",
     "xenia-ui",
+    "xenia-ui-spirv",
     "xxhash",
     "zlib",
   })
@@ -17,6 +19,41 @@ project("xenia-gpu")
   })
   includedirs({
     project_root.."/third_party/elemental-forms/src",
+    project_root.."/third_party/spirv-tools/external/include",
     project_root.."/build_tools/third_party/gflags/src",
   })
   local_platform_files()
+  
+group("src")
+project("xenia-gpu-shader-compiler")
+  uuid("ad76d3e4-4c62-439b-a0f6-f83fcf0e83c5")
+  kind("ConsoleApp")
+  language("C++")
+  links({
+    "gflags",
+    "spirv-tools",
+    "xenia-base",
+    "xenia-gpu",
+    "xenia-ui-spirv",
+  })
+  defines({
+  })
+  includedirs({
+    project_root.."/build_tools/third_party/gflags/src",
+  })
+  files({
+    "shader_compiler_main.cc",
+    "../base/main_"..platform_suffix..".cc",
+  })
+
+  filter("platforms:Windows")
+    -- Only create the .user file if it doesn't already exist.
+    local user_file = project_root.."/build/xenia-gpu-shader-compiler.vcxproj.user"
+    if not os.isfile(user_file) then
+      debugdir(project_root)
+      debugargs({
+        "--flagfile=scratch/flags.txt",
+        "2>&1",
+        "1>scratch/stdout-shader-compiler.txt",
+      })
+    end