Crypto/sys_fs: NPDRM decryption performance improvememts, memory usage reduction

[elad335]

• Previous PKG installer code was structured very naively: if 8GB read is requested, it would allocate 8GB of memory. Without considering recycling memory for each block.

TODO:

• Cache system for NPDRM reads in order to make PS3 filesystem reads much faster.
• Avoid reading entire data blocks if only few bytes are requested in decrypt_block, this should only apply when compression is not used inisde of the EDAT blocks.

Additional / Side effects:

• EDATADecrypter::ReadData is now thread-safe (due to use of local buffers instead of global, file::read_at instead of file::read). This fixes a race condition when using the syscall sys_fs_fcntl in block read mode.

[elad335]

Found another and more severe performance issue: when installing SDATs from PKG files data would first be decrypted as a mid-stage to disk, then loaded in whole to RAM, then flushed to destination as final decrypted data.
Instead of this atrocity it reads data now as needed and flushes final data as it reads the encrypted data, without writing out to disk mid-stage data nor keeping insane amounts in RAM.

[Megamouse]

signed mismatch

[Megamouse]

this should return a bool

[elad335]

Removed