file_util: const qualify IOFile's Tell and GetSize functions

src/common/file_util.cpp

@@ -930,12 +930,12 @@ bool IOFile::Close()
     return m_good;
 }
 
-u64 IOFile::GetSize()
+u64 IOFile::GetSize() const
 {
     if (IsOpen())
         return FileUtil::GetSize(m_file);
-    else
-        return 0;
+
+    return 0;
 }
 
 bool IOFile::Seek(s64 off, int origin)
@@ -946,12 +946,12 @@ bool IOFile::Seek(s64 off, int origin)
     return m_good;
 }
 
-u64 IOFile::Tell()
+u64 IOFile::Tell() const
 {
     if (IsOpen())
         return ftello(m_file);
-    else
-        return -1;
+
+    return -1;
 }
 
 bool IOFile::Flush()

src/common/file_util.h

@@ -247,8 +247,8 @@ public:
     explicit operator bool() const { return IsGood(); }
 
     bool Seek(s64 off, int origin);
-    u64 Tell();
-    u64 GetSize();
+    u64 Tell() const;
+    u64 GetSize() const;
     bool Resize(u64 size);
     bool Flush();