common sw_engine: code refactoring & stabilizing.

common sw_engine: code refactoring & stabilizing.

Apply tvg Array instead of std::vector

Also Fixed to compList in update() to passed by reference, not copying.
Also Fixed Composition Target memory leak

Here is the binary size result:

[libthorvg.so] 1785376 >> 1607416
[text] 121255 >> 118277
[data] 7792 >> 7736
[dec] 129119 >> 126085

Change-Id: I70ac0148ca69b4f38dd93099eab55259f9d5abe7