Update ImportAsMember test not to use unprototyped function.

We now reject this in Clang.

Author: jckarter

test/IDE/Inputs/custom-modules/ImportAsMember.h

@@ -11,7 +11,7 @@ extern double IAMStruct1GlobalVar
 extern struct IAMStruct1 IAMStruct1CreateSimple(double value)
     __attribute__((swift_name("Struct1.init(value:)")));
 
-extern struct IAMStruct1 IAMStruct1CreateSpecialLabel()
+extern struct IAMStruct1 IAMStruct1CreateSpecialLabel(void)
     __attribute__((swift_name("Struct1.init(specialLabel:)")));
 
 extern struct IAMStruct1 IAMStruct1Invert(struct IAMStruct1 s)