[libc++abi] Change LIBCXXABI_NO_TIMER to LIBCXXABI_USE_TIMER

[ldionne]

Summary

Instead of always defining LIBCXXABI_NO_TIMER to run the tests, only
define LIBCXXABI_USE_TIMER when we want to enable the timer. This makes
the libc++abi testing configuration simpler.

As a fly-by fix, remove the unused LIBUNWIND_NO_TIMER macro from libunwind.

[ldionne]

Fix incorrect #ifdef

libcxxabi/test/libcxxabi/test/config.py

class Configuration(LibcxxConfiguration):
 
     def configure_features(self):
         super(Configuration, self).configure_features()
         if not self.get_lit_bool('llvm_unwinder', False):
             self.config.available_features.add('libcxxabi-has-system-unwinder')
 
     def configure_compile_flags(self):
         self.cxx.compile_flags += [
-            '-DLIBCXXABI_NO_TIMER',
             '-D_LIBCPP_ENABLE_CXX17_REMOVED_UNEXPECTED_FUNCTIONS',
         ]
         if self.get_lit_bool('enable_exceptions', True):
             self.cxx.compile_flags += ['-funwind-tables']
         if not self.get_lit_bool('enable_threads', True):
             self.cxx.compile_flags += ['-D_LIBCXXABI_HAS_NO_THREADS']
             self.config.available_features.add('libcxxabi-no-threads')
         super(Configuration, self).configure_compile_flags()

libcxxabi/test/support/timer.h

 //===----------------------------------------------------------------------===////
 //
 // 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
 //
 //===----------------------------------------------------------------------===////
 
 #ifndef TIMER_H
 #define TIMER_H
 
-// Define LIBCXXABI_NO_TIMER to disable testing with a timer.
-#ifndef LIBCXXABI_NO_TIMER
+// Define LIBCXXABI_USE_TIMER to enable testing with a timer.
+#if defined(LIBCXXABI_USE_TIMER)
 
 #include <chrono>
 #include <cstdio>
 
 class timer
 {
     typedef std::chrono::high_resolution_clock Clock;
     typedef Clock::time_point TimePoint;
~timer()
         MicroSeconds us = duration_cast<MicroSeconds>(end - m_start);
         std::printf("%d microseconds\n", us.count());
     }
 
 private:
     TimePoint m_start;
 };
 
-#else /* LIBCXXABI_NO_TIMER */
+#else /* LIBCXXABI_USE_TIMER */
 
 class timer
 {
 public:
     timer() {}
     timer(timer const &) = delete;
     timer & operator=(timer const &) = delete;
     ~timer() {}
 };
 
-#endif /* LIBCXXABI_NO_TIMER */
+#endif /* LIBCXXABI_USE_TIMER */
 
 #endif /* TIMER_H */

libunwind/test/libunwind/test/config.py

def has_cpp_feature(self, feature, required_value):
         return int(self.cxx.dumpMacros().get('__cpp_' + feature, 0)) >= required_value
 
     def configure_features(self):
         super(Configuration, self).configure_features()
         if self.get_lit_bool('arm_ehabi', False):
             self.config.available_features.add('libunwind-arm-ehabi')
 
     def configure_compile_flags(self):
-        self.cxx.compile_flags += ['-DLIBUNWIND_NO_TIMER']
         # Stack unwinding tests need unwinding tables and these are not
         # generated by default on all Targets.
         self.cxx.compile_flags += ['-funwind-tables']
         # Make symbols available in the tests.
         triple = self.get_lit_conf('target_triple', None)
         if triple is not None and 'linux' in triple:
             self.cxx.link_flags += ['-Wl,--export-dynamic']
         if not self.get_lit_bool('enable_threads', True):