IOFile: Rename Clear() to ClearError() for clarity.

Source/Core/Common/IOFile.cpp

@@ -94,7 +94,7 @@ bool IOFile::Close()
 void IOFile::SetHandle(std::FILE* file)
 {
   Close();
-  Clear();
+  ClearError();
   m_file = file;
 }
 

Source/Core/Common/IOFile.h

@@ -103,7 +103,7 @@ public:
   bool Flush();
 
   // clear error state
-  void Clear()
+  void ClearError()
   {
     m_good = true;
     std::clearerr(m_file);

Source/Core/Common/LinearDiskCache.h

@@ -100,7 +100,7 @@ public:
 
         m_num_entries++;
       }
-      m_file.Clear();
+      m_file.ClearError();
       m_file.Seek(last_valid_value_start, File::SeekOrigin::Begin);
 
       return m_num_entries;