Better namespace CMake folders for Visual Studio

This helps Visual Studio users have less clutter in their solution
explorer. This also updates spirv-tools to a newer version that folders
itself. This also updates spirv-headers so that spirv-tools compiles.

CMakeLists.txt

diff --git a/CMakeLists.txt b/CMakeLists.txt
index f18c535..fe73cc9 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -58,7 +58,7 @@
 function(NXTExternalTarget folder target)
     set_property(TARGET ${target} APPEND PROPERTY COMPILE_OPTIONS ${NXT_FLAGS})
     set_property(TARGET ${target} APPEND PROPERTY COMPILE_DEFINITIONS ${NXT_DEFS})
-    set_property(TARGET ${target} PROPERTY FOLDER ${folder})
+    set_property(TARGET ${target} PROPERTY FOLDER "nxt/${folder}")
 endfunction()
 
 function(NXTInternalTarget folder target)

src/common/CMakeLists.txt

diff --git a/src/common/CMakeLists.txt b/src/common/CMakeLists.txt
index ec7dc65..de20bb2 100644
--- a/src/common/CMakeLists.txt
+++ b/src/common/CMakeLists.txt
@@ -27,4 +27,4 @@
 
 add_library(nxt_common STATIC ${COMMON_SOURCES})
 target_include_directories(nxt_common PUBLIC ${SRC_DIR})
-NXTInternalTarget("src" nxt_common)
+NXTInternalTarget("" nxt_common)

third_party/CMakeLists.txt

diff --git a/third_party/CMakeLists.txt b/third_party/CMakeLists.txt
index b4a4d4e..d92f167 100644
--- a/third_party/CMakeLists.txt
+++ b/third_party/CMakeLists.txt
@@ -40,7 +40,11 @@
 NXTExternalTarget("third_party" glad)
 
 # ShaderC
+# Prevent SPIRV-Tools from using Werror as it has a warning on MSVC
+set(SPIRV_WERROR OFF)
+# Don't add unnecessary shaderc targets
 set(SHADERC_SKIP_TESTS ON)
+# Help shaderc find the non-standard paths for its dependencies
 set(SHADERC_GOOGLE_TEST_DIR ${CMAKE_CURRENT_SOURCE_DIR}/googletest CACHE STRING "Location of googletest source")
 set(SHADERC_GLSLANG_DIR "${CMAKE_CURRENT_SOURCE_DIR}/glslang" CACHE STRING "Location of glslang source")
 set(SHADERC_SPIRV_TOOLS_DIR ${CMAKE_CURRENT_SOURCE_DIR}/spirv-tools CACHE STRING "Location of spirv-tools source")
@@ -50,8 +54,23 @@
 # Need to include this for spirv-tools to find it
 add_subdirectory(spirv-headers)
 add_subdirectory(shaderc)
-NXTExternalTarget("third_party" shaderc)
-NXTExternalTarget("third_party" shaderc_util)
+# Namespace the shaderc targets in a folder to avoid cluttering the
+# Visual Studio solution explorer
+set_target_properties(
+    add-copyright
+    build-version
+    check-copyright
+    glslc
+    glslc_exe
+    install-headers
+    shaderc
+    shaderc_util
+    shaderc_combined_genfile
+    shaderc-online-compile testdata
+    SPIRV-Headers-example
+    SPIRV-Headers-example-1.1
+    PROPERTIES FOLDER "third_party/shaderc"
+)
 
 # SPIRV-Cross
 add_library(spirv_cross STATIC

third_party/spirv-headers

diff --git a/third_party/spirv-headers b/third_party/spirv-headers
index 90dbe74..661ad91 160000
--- a/third_party/spirv-headers
+++ b/third_party/spirv-headers
@@ -1 +1 @@
-Subproject commit 90dbe74b1f182aed7c4bd1cdccf1426df1032c49
+Subproject commit 661ad91124e6af2272afd00f804d8aa276e17107

third_party/spirv-tools

diff --git a/third_party/spirv-tools b/third_party/spirv-tools
index f92e87a..06d4fd5 160000
--- a/third_party/spirv-tools
+++ b/third_party/spirv-tools
@@ -1 +1 @@
-Subproject commit f92e87a8f85915e8e0cbd39d0ca7fb004c0da05e
+Subproject commit 06d4fd52c244ee5abf6819f721b9f68e5a3fcdb0