Disable multi-threading for a Windows based OS.

This is a workaround for suspicious crashes/hanging ups happening
with lld-as-a-library.
TODO: ##677, needs to figure out exact reason.

llvm/CMakeLists.txt

@@ -517,7 +517,10 @@ option(LLVM_ENABLE_LIBEDIT "Use libedit if available." ON)
 option(LLVM_ENABLE_LIBPFM "Use libpfm for performance counters if available." ON)
 
 # On z/OS, threads cannot be used because TLS is not supported.
-if (CMAKE_SYSTEM_NAME MATCHES "OS390")
+# EraVM local begin
+# TODO: #677, investigate hanging up of solidity-compiler tests on windows.
+if (CMAKE_SYSTEM_NAME MATCHES "OS390" OR CMAKE_SYSTEM_NAME MATCHES "Windows")
+# EraVM local end
   option(LLVM_ENABLE_THREADS "Use threads if available." OFF)
 else()
   option(LLVM_ENABLE_THREADS "Use threads if available." ON)