Fixed a couple correctness issues

Author: Michael-F-Bryan

src/execution_engine.rs

@@ -91,7 +91,7 @@ impl ExecutionEngine {
     ///
     /// assert_eq!(result, 128.);
     /// ```
-    pub fn add_global_mapping(&self, value: &AnyValue, addr: usize) {
+    pub fn add_global_mapping(&mut self, value: &AnyValue, addr: usize) {
         unsafe {
             LLVMAddGlobalMapping(*self.execution_engine, value.as_value_ref(), addr as *mut _)
         }
@@ -114,7 +114,7 @@ impl ExecutionEngine {
     ///
     /// assert!(ee.add_module(&module).is_err());
     /// ```
-    pub fn add_module(&self, module: &Module) -> Result<(), ()> {
+    pub fn add_module(&mut self, module: &Module) -> Result<(), ()> {
         unsafe {
             LLVMAddModule(*self.execution_engine, module.module.get())
         }
@@ -128,7 +128,7 @@ impl ExecutionEngine {
         Ok(())
     }
 
-    pub fn remove_module(&self, module: &Module) -> Result<(), String> {
+    pub fn remove_module(&mut self, module: &Module) -> Result<(), String> {
         match *module.owned_by_ee.borrow() {
             Some(ref ee) if *ee.execution_engine != *self.execution_engine => return Err("Module is not owned by this Execution Engine".into()),
             None => return Err("Module is not owned by an Execution Engine".into()),
@@ -169,7 +169,7 @@ impl ExecutionEngine {
     /// "C"` functions can be retrieved via the `get_function()` method. If you
     /// get funny type errors then it's probably because you have specified the
     /// wrong calling convention or forgotten to specify the retrieved function
-    /// is `unsafe`.
+    /// as `unsafe`.
     /// 
     /// # Examples
     /// 
@@ -287,10 +287,10 @@ impl ExecutionEngine {
 
     pub fn run_function_as_main(&self, function: &FunctionValue) {
         let args = vec![]; // TODO: Support argc, argv
-        let env_p = vec![]; // REVIEW: No clue what this is
+        let environment_variables = vec![];
 
         unsafe {
-            LLVMRunFunctionAsMain(*self.execution_engine, function.as_value_ref(), args.len() as u32, args.as_ptr(), env_p.as_ptr()); // REVIEW: usize to u32 cast ok??
+            LLVMRunFunctionAsMain(*self.execution_engine, function.as_value_ref(), args.len() as u32, args.as_ptr(), environment_variables.as_ptr()); // REVIEW: usize to u32 cast ok??
         }
     }