Set output names for libcxx shared libraries

Although building shared libraries is not enabled, CMake still creates
targets for them, and implicitly changes them to static. In order to
prevent this duplication of library targets, this patch explicitly
sets the output names for shared libraries to something different.

Author: dcandler

CMakeLists.txt

@@ -1249,6 +1249,7 @@ function(
         -DLIBCXXABI_USE_COMPILER_RT=ON
         -DLIBCXXABI_USE_LLVM_UNWINDER=ON
         -DLIBCXXABI_TEST_PARAMS=executor=${test_executor}
+        -DLIBCXXABI_SHARED_OUTPUT_NAME="c++abi-shared"
         -DLIBCXX_ABI_UNSTABLE=ON
         -DLIBCXX_CXX_ABI=libcxxabi
         -DLIBCXX_STATICALLY_LINK_ABI_IN_STATIC_LIBRARY=ON
@@ -1257,12 +1258,14 @@ function(
         -DLIBCXX_ENABLE_STATIC=ON
         -DLIBCXX_INCLUDE_BENCHMARKS=OFF
         -DLIBCXX_TEST_PARAMS=executor=${test_executor}
+        -DLIBCXX_SHARED_OUTPUT_NAME="c++-shared"
         -DLIBUNWIND_ENABLE_SHARED=OFF
         -DLIBUNWIND_ENABLE_STATIC=ON
         -DLIBUNWIND_IS_BAREMETAL=ON
         -DLIBUNWIND_REMEMBER_HEAP_ALLOC=ON
         -DLIBUNWIND_USE_COMPILER_RT=ON
         -DLIBUNWIND_TEST_PARAMS=executor=${test_executor}
+        -DLIBUNWIND_SHARED_OUTPUT_NAME="unwind-shared"
         -DLLVM_LIT_ARGS=${LLVM_LIT_ARGS}
         -DLLVM_ENABLE_RUNTIMES=libcxxabi,libcxx,libunwind
         -DRUNTIME_TEST_ARCH_FLAGS=${flags}