[NFCI] Clean up exceptions related CMake and Lit options in libc++abi and libunwind

First, libc++abi doesn't need to add the no-exceptions Lit feature itself,
since that is already done in the config.py for libc++, which it reuses.
Specifically, config.enable_exceptions is set based on @LIBCXXABI_ENABLE_EXCEPTIONS@
in libc++abi's lit.cfg.in, and libc++'s config.py handles that correctly.

Secondly, libunwind's LIBUNWIND_ENABLE_EXCEPTIONS is never set (it's
probably a remnant of copy-pasting code between the runtime libraries),
so the library is always built with exceptions disabled (which makes
sense since it implements the runtime support for exceptions).
Conversely, the test suite is always run with exceptions enabled
(not sure why), but that is preserved by the default behavior of
libc++'s config.py.

GitOrigin-RevId: 0e04342ae0399876f3488464d12f5a4da5085456
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index 40d4acd..e608c17 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -15,7 +15,6 @@
 pythonize_bool(LIBCXX_ENABLE_SHARED)
 pythonize_bool(LIBUNWIND_ENABLE_SHARED)
 pythonize_bool(LIBUNWIND_ENABLE_THREADS)
-pythonize_bool(LIBUNWIND_ENABLE_EXCEPTIONS)
 pythonize_bool(LIBUNWIND_USES_ARM_EHABI)
 pythonize_bool(LIBUNWIND_USE_COMPILER_RT)
 pythonize_bool(LIBUNWIND_BUILD_EXTERNAL_THREAD_LIBRARY)
diff --git a/test/libunwind/test/config.py b/test/libunwind/test/config.py
index 36501f2..7e4f230 100644
--- a/test/libunwind/test/config.py
+++ b/test/libunwind/test/config.py
@@ -35,15 +35,11 @@
 
     def configure_features(self):
         super(Configuration, self).configure_features()
-        if not self.get_lit_bool('enable_exceptions', True):
-            self.config.available_features.add('no-exceptions')
         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']
-        if not self.get_lit_bool('enable_exceptions', True):
-            self.cxx.compile_flags += ['-fno-exceptions', '-DLIBUNWIND_HAS_NO_EXCEPTIONS']
         # Stack unwinding tests need unwinding tables and these are not
         # generated by default on all Targets.
         self.cxx.compile_flags += ['-funwind-tables']
diff --git a/test/lit.cfg b/test/lit.cfg
index 262f25a..7f74bd6 100644
--- a/test/lit.cfg
+++ b/test/lit.cfg
@@ -23,9 +23,6 @@
 # test_source_root: The root path where tests are located.
 config.test_source_root = os.path.dirname(__file__)
 
-# needed to test libunwind with code that throws exceptions
-config.enable_exceptions = True
-
 # Infer the libcxx_test_source_root for configuration import.
 # If libcxx_source_root isn't specified in the config, assume that the libcxx
 # and libunwind source directories are sibling directories.
diff --git a/test/lit.site.cfg.in b/test/lit.site.cfg.in
index 37f90a9..809ad10 100644
--- a/test/lit.site.cfg.in
+++ b/test/lit.site.cfg.in
@@ -18,7 +18,6 @@
 config.executor                 = "@LIBUNWIND_EXECUTOR@"
 config.libunwind_shared         = @LIBUNWIND_ENABLE_SHARED@
 config.enable_shared            = @LIBCXX_ENABLE_SHARED@
-config.enable_exceptions        = @LIBUNWIND_ENABLE_EXCEPTIONS@
 config.arm_ehabi                = @LIBUNWIND_USES_ARM_EHABI@
 config.host_triple              = "@LLVM_HOST_TRIPLE@"
 config.target_triple            = "@TARGET_TRIPLE@"