build: explicitly set the linker language for unwind

The unwinder should not depend on libc++.  In fact, we do not end up
with a link against libc++ as we do not have a dependency on libc++ at
runtime.  This ensures that we link with `clang` rather than `clang++`.

Author: compnerd

libunwind/src/CMakeLists.txt

@@ -127,6 +127,8 @@ if (LIBUNWIND_ENABLE_SHARED)
                             "${LIBUNWIND_COMPILE_FLAGS}"
                           LINK_FLAGS
                             "${LIBUNWIND_LINK_FLAGS}"
+                          LINKER_LANGUAGE
+                            C
                           OUTPUT_NAME
                             "unwind"
                           VERSION