[ubsan] Remove ubsan_standalone_cxx shared library.

[eugenis]

Summary

Link everything, including the C++ bits, in the single
ubsan_standalone SHARED library. This matches ASan setup.

[eugenis]

Note that Clang driver never links UBSan as a shared library, which means that this configuration is completely untested and also that this change is 100% safe.
This build rule was added in https://reviews.llvm.org/D33216.
I'm working on Android testing for ubsan-standalone that would exercise this library.

[eugenis]

Remove -> Merge.

compiler-rt/lib/ubsan/CMakeLists.txt

if(COMPILER_RT_HAS_UBSAN)
 
     if (UNIX)
       add_compiler_rt_runtime(clang_rt.ubsan_standalone
         SHARED
         ARCHS ${UBSAN_SUPPORTED_ARCH}
         OBJECT_LIBS RTSanitizerCommon
               RTSanitizerCommonLibc
               RTUbsan
+              RTUbsan_cxx
               RTUbsan_standalone
               RTInterception
         CFLAGS ${UBSAN_CFLAGS}
         LINK_FLAGS ${SANITIZER_COMMON_LINK_FLAGS}
         LINK_LIBS ${UBSAN_DYNAMIC_LIBS}
         PARENT_TARGET ubsan)
 
-      add_compiler_rt_runtime(clang_rt.ubsan_standalone_cxx
-        SHARED
-        ARCHS ${UBSAN_SUPPORTED_ARCH}
-        OBJECT_LIBS RTSanitizerCommon
-                RTSanitizerCommonLibc
-                RTUbsan
-                RTUbsan_cxx
-        CFLAGS ${UBSAN_CXXFLAGS}
-        LINK_FLAGS ${SANITIZER_COMMON_LINK_FLAGS}
-        LINK_LIBS ${UBSAN_DYNAMIC_LIBS}
-        PARENT_TARGET ubsan)
-
       set(ARCHS_FOR_SYMBOLS ${UBSAN_SUPPORTED_ARCH})
       list(REMOVE_ITEM ARCHS_FOR_SYMBOLS i386)
       add_sanitizer_rt_symbols(clang_rt.ubsan_standalone
         ARCHS ${ARCHS_FOR_SYMBOLS}
         PARENT_TARGET ubsan
         EXTRA ubsan.syms.extra)
       add_sanitizer_rt_symbols(clang_rt.ubsan_standalone_cxx
         ARCHS ${ARCHS_FOR_SYMBOLS}
         PARENT_TARGET ubsan
         EXTRA ubsan.syms.extra)
     endif()
   endif()
 endif()