fix small error

src/AssemblyGenerator.cpp

@@ -37,7 +37,7 @@ AssemblyGenerator::AssemblyGenerator(std::ostream& out) :
     out{ out }
 {
     write(".globl ", LabelNames::main);
-    write(generateLabel(LabelNames::main));
+    write(LabelNames::main, ":");
     write("subq $40, %rsp");
     write("movq $131072, %", argumentRegister1);
     write("movq $1, %", argumentRegister2);

src/AssemblyGenerator.h

@@ -32,6 +32,8 @@ struct zp::LabelNames
     static const char* main;
     static const char* getchar;
     static const char* putchar;
+    static const char* calloc;
+    static const char* free;
 };