[libcxx] [test] Add missing <stdexcept> in several tests.

Reviewed as https://reviews.llvm.org/D50420

llvm-svn: 339209
diff --git a/libcxx/test/std/strings/string.conversions/stol.pass.cpp b/libcxx/test/std/strings/string.conversions/stol.pass.cpp
index 5e16735..4815436 100644
--- a/libcxx/test/std/strings/string.conversions/stol.pass.cpp
+++ b/libcxx/test/std/strings/string.conversions/stol.pass.cpp
@@ -18,6 +18,7 @@
 
 #include <string>
 #include <cassert>
+#include <stdexcept>
 
 #include "test_macros.h"