[libc] Fix warning in ExecuteFunctionUnix.cpp

WIFEXITED and friends expect an `int *` but these methods
were marked `const` so they instead got a `const int *`.
This macros aren't actually modifying their argument, but
we were never using these functions on an immutable
`ProcessStatus` type anyway.

Author: abrachet

libc/utils/testutils/ExecuteFunction.h

@@ -35,9 +35,9 @@ struct ProcessStatus {
     return failure == reinterpret_cast<const char *>(TIMEOUT);
   }
   const char *get_error() const { return timed_out() ? nullptr : failure; }
-  bool exited_normally() const;
-  int get_exit_code() const;
-  int get_fatal_signal() const;
+  bool exited_normally();
+  int get_exit_code();
+  int get_fatal_signal();
 };
 
 ProcessStatus invoke_in_subprocess(FunctionCaller *func,

libc/utils/testutils/ExecuteFunctionUnix.cpp

@@ -20,16 +20,14 @@
 namespace __llvm_libc {
 namespace testutils {
 
-bool ProcessStatus::exited_normally() const {
-  return WIFEXITED(platform_defined);
-}
+bool ProcessStatus::exited_normally() { return WIFEXITED(platform_defined); }
 
-int ProcessStatus::get_exit_code() const {
+int ProcessStatus::get_exit_code() {
   assert(exited_normally() && "Abnormal termination, no exit code");
   return WEXITSTATUS(platform_defined);
 }
 
-int ProcessStatus::get_fatal_signal() const {
+int ProcessStatus::get_fatal_signal() {
   if (exited_normally())
     return 0;
   return WTERMSIG(platform_defined);