fix the fix for #9791 - proper return values! (#9794)

- omc_rename returns zero on success
- SystemImpl__rename returns true on success

OMCompiler/Compiler/Util/System.mo

@@ -1119,7 +1119,7 @@ public function fileContentsEqual
   external "C" result = SystemImpl__fileContentsEqual(file1,file2) annotation(Library = {"omcruntime"});
 end fileContentsEqual;
 
-public function rename
+public function rename "returns true if success, false otherwise"
   input String source;
   input String dest;
   output Boolean result;

OMCompiler/Compiler/runtime/systemimpl.c

@@ -2992,7 +2992,7 @@ int SystemImpl__fileContentsEqual(const char *file1, const char *file2)
 
 int SystemImpl__rename(const char *source, const char *dest)
 {
-   return omc_rename(source, dest);
+   return (0 == omc_rename(source, dest));
 }
 
 char* SystemImpl__ctime(double time)

OMCompiler/SimulationRuntime/c/util/omc_file.c

@@ -240,11 +240,16 @@ int omc_unlink(const char *filename) {
   return result;
 }
 
+// zero on success, anything else on failure!
 int omc_rename(const char *source, const char *dest) {
 #if defined(__MINGW32__) || defined(_MSC_VER)
-  return MoveFileEx(source, dest, MOVEFILE_REPLACE_EXISTING);
+  // If the function succeeds, the return value is nonzero.
+  // If the function fails, the return value is zero (0). To get extended error information, call GetLastError.
+  return !MoveFileEx(source, dest, MOVEFILE_REPLACE_EXISTING);
 #endif
-  return 0==rename(source,dest);
+  // On success, zero is returned.  On error, -1 is returned, and
+  // errno is set to indicate the error.
+  return rename(source,dest);
 }
 
 #if defined(__MINGW32__) || defined(_MSC_VER)