[libc++] Remove support for specifying LIBCXX_CXX_ABI_SYSTEM manually
This was only kept until Chromium fixed their build of libc++, which
they have now done according to
https://bugs.chromium.org/p/chromium/issues/detail?id=1067216
diff --git a/libcxx/cmake/Modules/HandleLibCXXABI.cmake b/libcxx/cmake/Modules/HandleLibCXXABI.cmake
index f5d15f8..a62efc0 100644
--- a/libcxx/cmake/Modules/HandleLibCXXABI.cmake
+++ b/libcxx/cmake/Modules/HandleLibCXXABI.cmake
@@ -104,7 +104,7 @@
elseif ("${LIBCXX_CXX_ABI_LIBNAME}" STREQUAL "libcxxabi")
set(LIBCXX_CXX_ABI_INCLUDE_PATHS "${LIBCXX_SOURCE_DIR}/../libcxxabi/include")
- if((LIBCXX_CXX_ABI_SYSTEM OR LIBCXX_STANDALONE_BUILD) AND NOT (LIBCXX_CXX_ABI_INTREE OR HAVE_LIBCXXABI))
+ if(LIBCXX_STANDALONE_BUILD AND NOT (LIBCXX_CXX_ABI_INTREE OR HAVE_LIBCXXABI))
set(shared c++abi)
set(static c++abi)
else()
