remove the pthread library as we don't use it.

theano/scan_module/scan_perform_ext.py

@@ -51,7 +51,7 @@ except ImportError:
             loc = os.path.join(config.compiledir, dirname)
             if not os.path.exists(loc):
                 os.mkdir(loc)
-            preargs = ['-pthread', '-fwrapv', '-O2', '-fno-strict-aliasing']
+            preargs = ['-fwrapv', '-O2', '-fno-strict-aliasing']
             preargs += cmodule.GCC_compiler.compile_args()
             cmodule.GCC_compiler.compile_str(dirname, code, location=loc,
                                              preargs=preargs)