remove usage of DXSDK for mingw, breaks compilation if included in some versions (nw)

scripts/bgfx.lua

@@ -76,7 +76,7 @@ function bgfxProject(_name, _kind, _defines)
 				"GLESv2",
 			}
 
-		configuration { "mingw* or vs2008" }
+		configuration { "vs2008" }
 			includedirs {
 				"$(DXSDK_DIR)/include",
 			}

scripts/example-common.lua

@@ -37,7 +37,7 @@ project ("example-common")
 		}
 	end
 
-	configuration { "mingw* or vs2008" }
+	configuration { "vs2008" }
 		includedirs {
 			"$(DXSDK_DIR)/include",
 		}

scripts/shaderc.lua

@@ -51,6 +51,7 @@ project "shaderc"
 			"$(DXSDK_DIR)/include",
 		}
 
+	configuration { "vs*" }
 		links {
 			"d3dx9",
 			"d3dcompiler",