[libcxx{,abi}] Emit deplibs only when detected by CMake
This is a followup to 35bc5276ca3. It fixes the dependent libs usage
in libcxx and libcxxabi to link pthread and rt libraries only if CMake
detects them, rather than based on explicit platform blacklist.
Differential Revision: https://reviews.llvm.org/D70888
diff --git a/libcxx/src/debug.cpp b/libcxx/src/debug.cpp
index 1f5ce10..20055fc 100644
--- a/libcxx/src/debug.cpp
+++ b/libcxx/src/debug.cpp
@@ -15,7 +15,7 @@
#include "__hash_table"
#ifndef _LIBCPP_HAS_NO_THREADS
#include "mutex"
-#if defined(__unix__) && !defined(__ANDROID__) && defined(__ELF__) && defined(_LIBCPP_HAS_COMMENT_LIB_PRAGMA)
+#if defined(__ELF__) && defined(_LIBCPP_LINK_PTHREAD_LIB)
#pragma comment(lib, "pthread")
#endif
#endif