clang: warning: argument unused during compilation: '-pthread'
Undefined symbols for architecture x86_64:
  "_XML_ErrorString", referenced from:
      _FcConfigParseAndLoad in libfontconfig.a(fcxml.o)
  "_XML_GetBuffer", referenced from:
      _FcConfigParseAndLoad in libfontconfig.a(fcxml.o)
  "_XML_GetCurrentLineNumber", referenced from:
      _FcConfigMessage in libfontconfig.a(fcxml.o)
  "_XML_GetErrorCode", referenced from:
      _FcConfigParseAndLoad in libfontconfig.a(fcxml.o)
  "_XML_ParseBuffer", referenced from:
      _FcConfigParseAndLoad in libfontconfig.a(fcxml.o)
  "_XML_ParserCreate", referenced from:
      _FcConfigParseAndLoad in libfontconfig.a(fcxml.o)
  "_XML_ParserFree", referenced from:
      _FcConfigParseAndLoad in libfontconfig.a(fcxml.o)
  "_XML_SetCharacterDataHandler", referenced from:
      _FcConfigParseAndLoad in libfontconfig.a(fcxml.o)
  "_XML_SetDoctypeDeclHandler", referenced from:
      _FcConfigParseAndLoad in libfontconfig.a(fcxml.o)
  "_XML_SetElementHandler", referenced from:
      _FcConfigParseAndLoad in libfontconfig.a(fcxml.o)
  "_XML_SetUserData", referenced from:
      _FcConfigParseAndLoad in libfontconfig.a(fcxml.o)
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
ERROR: fontconfig not found using pkg-config