[Clang] Fix constexpr alloc tests on 32 bits platforms

[cor3ntin]

Summary

Some bots were broken by 45ab2b48bd55

clang/test/SemaCXX/cxx2a-constexpr-dynalloc-limits.cpp

struct S {
 
     constexpr ~S() {
         alloc.deallocate(data);
     }
     std::allocator<T> alloc;
     T* data;
 };
 
-constexpr std::size_t s = S<std::size_t>(1099511627777)[42]; // expected-error {{constexpr variable 's' must be initialized by a constant expression}} \
-                                           // expected-note@#call {{in call to 'this->alloc.allocate(1099511627777)'}} \
-                                           // expected-note@#alloc {{cannot allocate array; evaluated array bound 1099511627777 is too large}} \
-                                           // expected-note {{in call to 'S(1099511627777)'}}
+// Only run these tests on 64 bits platforms
+#if __LP64__
+constexpr std::size_t s = S<std::size_t>(~0UL)[42]; // expected-error {{constexpr variable 's' must be initialized by a constant expression}} \
+                                           // expected-note-re@#call {{in call to 'this->alloc.allocate({{.*}})'}} \
+                                           // expected-note-re@#alloc {{cannot allocate array; evaluated array bound {{.*}} is too large}} \
+                                           // expected-note-re {{in call to 'S({{.*}})'}}
+#endif
 // Check that we do not try to fold very large arrays
-std::size_t s2 = S<std::size_t>(1099511627777)[42];
+std::size_t s2 = S<std::size_t>(~0UL)[42];
 std::size_t s3 = S<std::size_t>(~0ULL)[42];
 
 // We can allocate and initialize a small array
 constexpr std::size_t ssmall = S<std::size_t>(100)[42];
 
 // We can allocate this array but we hikt the number of steps
 constexpr std::size_t s4 = S<std::size_t>(1024)[42]; // expected-error {{constexpr variable 's4' must be initialized by a constant expression}} \
                                    // expected-note@#construct {{constexpr evaluation hit maximum step limit; possible infinite loop?}} \