Fix some errors from Clang compiler (#4915)

Fix some errors from Clang compiler (#4915)

* Fix some errors from Clang compiler

* Fix abs on unsigned char, fix hidden overloaded virtual function, rename predeclared class on struct, remove unused private variable, remove std::move when he called in return statement

Signed-off-by: Pavel Iliutchenko <p.iliutchenk@samsung.com>
* Fix unused variables, struct/class mismatching

Signed-off-by: Pavel Iliutchenko <p.iliutchenk@samsung.com>
* Fix extern C++, unused variables, explicit overriding, remove std::move in return statement

Signed-off-by: Pavel Iliutchenko <p.iliutchenk@samsung.com>
* Fix file for format-check and extern C

Signed-off-by: Pavel Iliutchenko <p.iliutchenk@samsung.com>
* Fix library information removing from neurun

Signed-off-by: Pavel Iliutchenko <p.iliutchenk@samsung.com>