Bump GCC constexpr limit

Author: ldionne

libcxx/test/std/algorithms/alg.sorting/alg.sort/stable.sort/stable_sort.pass.cpp

@@ -13,7 +13,7 @@
 //     stable_sort(RandomAccessIterator first, RandomAccessIterator last);
 
 // ADDITIONAL_COMPILE_FLAGS(has-fconstexpr-steps): -fconstexpr-steps=20000000
-// ADDITIONAL_COMPILE_FLAGS(has-fconstexpr-ops-limit): -fconstexpr-ops-limit=100000000
+// ADDITIONAL_COMPILE_FLAGS(has-fconstexpr-ops-limit): -fconstexpr-ops-limit=200000000
 
 #include <algorithm>
 #include <cassert>