[sanitizer] Set cxx-abi library for ubsan_minimal

[eugenis]

Is that for <atomic> implementation? It is normally in CXX, not CXXABI, so this it not entirely correct.
Besides, ubsan-minimal does not link with -nodefaultlibs (because it does not use SANITIZER_COMMON_LINK_FLAGS). It should not need this.

Does it help to add -stdlib=libc++ to both cflags and linkflags?

[eugenis]

I think I see your problem.
If I build compiler-rt against Android NDK toolchain with

-DSANITIZER_CXX_ABI=none
-DSANITIZER_CXX_ABI_LIBRARY="unwind;c++abi"

, all sanitizer libraries link c++abi stuff statically, but ubsan_minimal still gets a dependency on libc++_shared.so.

My build succeeds, so you might have a different problem after all.
But the end result is still broken, we want a way to build ubsan_minimal without runtime dependency on libc++.

[eugenis]

Perhaps the right solution is to switch to C11 atomics.
We don't need libc++ for anything else here, and don't plan to introduce new dependencies.

[eugenis]

https://reviews.llvm.org/D39934

lib/ubsan_minimal/CMakeLists.txt

 # Build for the undefined behavior sanitizer runtime support library.
 
 set(UBSAN_MINIMAL_SOURCES
   ubsan_minimal_handlers.cc
   )
 
 include_directories(..)
 
 set(UBSAN_CFLAGS ${SANITIZER_COMMON_CFLAGS})
 append_rtti_flag(OFF UBSAN_CFLAGS)
 
 set(UBSAN_STANDALONE_CFLAGS ${SANITIZER_COMMON_CFLAGS})
 append_rtti_flag(OFF UBSAN_STANDALONE_CFLAGS)
 
+set(UBSAN_DYNAMIC_LIBS ${SANITIZER_CXX_ABI_LIBRARY} ${SANITIZER_COMMON_LINK_LIBS})
+
 add_compiler_rt_component(ubsan-minimal)
 
 # Common parts of UBSan runtime.
 add_compiler_rt_object_libraries(RTUbsan_minimal
   OS ${SANITIZER_COMMON_SUPPORTED_OS}
   ARCHS ${UBSAN_COMMON_SUPPORTED_ARCH}
   SOURCES ${UBSAN_MINIMAL_SOURCES} CFLAGS ${UBSAN_CFLAGS})