[compiler-rt][asan] Enable unwind-tables for Arm Linux

Since https://reviews.llvm.org/D102046 some tests have
been falling back to fast unwinding on our Thumb bot.

This fails because fast unwinding does not work on Thumb.
By adding the extra information we ensure this does not happen
during testing, but the built library can still fast unwind
as a last resort.

Since there are some situations it can work in, like if
eveything is built with clang. During testing we've got gcc
built system libs and clang built tests.

The same change was made for sanitizer-common in
https://reviews.llvm.org/D96337.

Reviewed By: zatrazz

Differential Revision: https://reviews.llvm.org/D103463

compiler-rt/test/asan/CMakeLists.txt

@@ -71,6 +71,12 @@ foreach(arch ${ASAN_TEST_ARCH})
     list(APPEND ASAN_DYNAMIC_TESTSUITES
       ${CMAKE_CURRENT_BINARY_DIR}/${CONFIG_NAME})
   endif()
+
+  # ARM on Linux may include thumb code, where fast unwinding does not work.
+  # Enable unwind tables so that we do not end up falling back to it in tests.
+  if ("${CMAKE_SYSTEM_NAME}" STREQUAL "Linux" AND NOT ANDROID AND ${arch} MATCHES "arm")
+    set(ASAN_TEST_TARGET_CFLAGS "${ASAN_TEST_TARGET_CFLAGS} -funwind-tables")
+  endif()
 endforeach()
 
 # iOS and iOS simulator test suites