[libcxx][test] Make string.modifiers/clear_and_shrink_db1.pass.cpp a regular mode test

[krisb]

Summary

Turn this test into a normal mode as it contains well-formed code and
checks for defined behavior. It still can be run in debug mode as of D100866.

[• Quuxplusone]

If buildkite is happy with this, I'm happy. (I'm mildly confused why this test wanted to redefine _LIBCPP_ASSERT in the first place.)

libcxx/test/libcxx/strings/basic.string/string.modifiers/clear_and_shrink.pass.cpp

39

Please add return 0; at the end of main here, for consistency with 2df59c50688c122bbcae7467d3eaf862c3ea3088 . (I don't know why it was missed in that commit, and I don't think it matters.)

libcxx/test/libcxx/strings/basic.string/string.modifiers/clear_and_shrink.pass.cpp

 //===----------------------------------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 // <string>
 
 // Call __clear_and_shrink() and ensure string invariants hold
 
-// UNSUPPORTED: libcxx-no-debug-mode
-
-// ADDITIONAL_COMPILE_FLAGS: -D_LIBCPP_DEBUG=1
-#define _LIBCPP_ASSERT(x, m) ((x) ? (void)0 : std::exit(0))
-
 #include <string>
 #include <cassert>
 
 #include "test_macros.h"
 
 int main(int, char**)
 {
     std::string l = "Long string so that allocation definitely, for sure, absolutely happens. Probably.";
     std::string s = "short";
 
     assert(l.__invariants());
     assert(s.__invariants());
 
     s.__clear_and_shrink();
     assert(s.__invariants());
     assert(s.size() == 0);
 
     {
     std::string::size_type cap = l.capacity();
     l.__clear_and_shrink();
     assert(l.__invariants());
     assert(l.size() == 0);
     assert(l.capacity() < cap);
     }
+
+    return 0;
 }