Swift 4.2 + SwiftPM package? (Edit: Swift 5.0)

The package manager seems to be capable of building swift-5.0-RELEASE, but Xcode failed to build llvmSupport again on a clean build. This is the error message:

Undefined symbols for architecture x86_64:
  "_del_curterm", referenced from:
      terminalHasColors(int) in Process.o
  "_set_curterm", referenced from:
      terminalHasColors(int) in Process.o
  "_setupterm", referenced from:
      terminalHasColors(int) in Process.o
  "_tigetnum", referenced from:
      terminalHasColors(int) in Process.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)