[tools] [unittests] Add missing include headers

Author: HassanElDesouky

tools/swift-def-to-yaml-converter/swift-def-to-yaml-converter.cpp

@@ -25,6 +25,8 @@
 #include "llvm/Support/Path.h"
 #include "llvm/Support/raw_ostream.h"
 #include <cstdlib>
+#include <string>
+#include <system_error>
 
 static constexpr const char *const diagnosticID[] = {
 #define DIAG(KIND, ID, Options, Text, Signature) #ID,

unittests/DefToYAMLConverter/DefToYAMLConverterTest.cpp

@@ -20,6 +20,7 @@
 #include "llvm/Support/raw_ostream.h"
 #include "gtest/gtest.h"
 #include <random>
+#include <string>
 
 using namespace swift;
 using namespace swift::diag;