Remove syscall builtin.

artiq/compiler/builtins.py

@@ -150,9 +150,6 @@ def fn_print():
 def fn_kernel():
     return types.TBuiltinFunction("kernel")
 
-def fn_syscall():
-    return types.TBuiltinFunction("syscall")
-
 # Accessors
 
 def is_none(typ):

artiq/compiler/prelude.py

@@ -20,5 +20,4 @@ def globals():
         "round":                builtins.fn_round(),
         "print":                builtins.fn_print(),
         "kernel":               builtins.fn_kernel(),
-        "syscall":              builtins.fn_syscall(),
     }

artiq/compiler/transforms/inferencer.py

@@ -666,10 +666,6 @@ class Inferencer(algorithm.Visitor):
                 pass
             else:
                 diagnose(valid_forms())
-        # TODO: add when it is clear what interface syscall() has
-        # elif types.is_builtin(typ, "syscall"):
-        #     valid_Forms = lambda: [
-        #     ]
 
     def visit_CallT(self, node):
         self.generic_visit(node)