Add new static targets to VS solution folders

`GenericCodeGen` and `MachineIndependent` were missing from the generated visual studio solutions. Add these.
diff --git a/glslang/CMakeLists.txt b/glslang/CMakeLists.txt
index 98c8145..b0bfce8 100644
--- a/glslang/CMakeLists.txt
+++ b/glslang/CMakeLists.txt
@@ -50,6 +50,7 @@
 add_library(GenericCodeGen STATIC
     GenericCodeGen/CodeGen.cpp
     GenericCodeGen/Link.cpp)
+set_property(TARGET GenericCodeGen PROPERTY FOLDER glslang)
 
 ################################################################################
 # MachineIndependent
@@ -129,7 +130,7 @@
 endif(ENABLE_HLSL)
 
 add_library(MachineIndependent STATIC ${MACHINEINDEPENDENT_SOURCES} ${MACHINEINDEPENDENT_HEADERS})
-
+set_property(TARGET MachineIndependent PROPERTY FOLDER glslang)
 glslang_pch(SOURCES MachineIndependent/pch.cpp)
 
 target_link_libraries(MachineIndependent PRIVATE OGLCompiler OSDependent GenericCodeGen)