Fixing include-what-you-use in SPIR-V parser

Change-Id: If9eeb92dd50bd88e3dcc8b0a8966812a96a153a2
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/17287
Reviewed-by: dan sinclair <dsinclair@google.com>

src/reader/spirv/parser_impl.cc

@@ -15,6 +15,8 @@
 #include "src/reader/spirv/parser_impl.h"
 
 #include <cstring>
+#include <string>
+#include <utility>
 
 #include "source/opt/build_module.h"
 #include "spirv-tools/libspirv.hpp"

src/reader/spirv/parser_impl.h

@@ -18,6 +18,7 @@
 #include <cstdint>
 #include <memory>
 #include <sstream>
+#include <string>
 #include <unordered_map>
 #include <unordered_set>
 #include <vector>