Add missing include headers

This is for C++ modules build in chromium.

This imports
https://github.com/KhronosGroup/SPIRV-Tools/pull/5995

Bug: 40263312
Change-Id: I175059687a3f7d03b56a7eb9c776a679cced1560
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/75048
Presubmit-Ready: Takuto Ikuta <tikuta@google.com>
Tested-by: Takuto Ikuta <tikuta@google.com>
Reviewed-by: Geoff Lang <geofflang@google.com>
Kokoro-Result: kokoro <noreply+kokoro@google.com>
Commit-Queue: Takuto Ikuta <tikuta@google.com>

third_party/SPIRV-Tools/tools/util/flags.cpp

diff --git a/third_party/SPIRV-Tools/tools/util/flags.cpp b/third_party/SPIRV-Tools/tools/util/flags.cpp
index 6198e4b..9c99677 100644
--- a/third_party/SPIRV-Tools/tools/util/flags.cpp
+++ b/third_party/SPIRV-Tools/tools/util/flags.cpp
@@ -15,6 +15,7 @@
 #include "flags.h"
 
 #include <algorithm>
+#include <cerrno>
 #include <cstdlib>
 #include <cstring>
 #include <iostream>