Allow booting any ELF inside disc directory, not just ones at 'PS3_GAME/USRDIR/'

[elad335]

1. Disable incorrect error check which checks for a PARAM.SFO mismatch between the one at "elf-path/../../PARAM.SFO" and "/dev_bdvd/PS3_GAME/PARAM.SFO", allows to boot any ELF within any subdirectory of "/dev_bdvd/PS3_GAME/USRDIR". This also includes loading of PRX/OVL inside the game files.
2. Improve disc directory search by searching the PS3_DISC.SFB closest to root directory, in case there is such file in game files.
3. Mount /dev_bdvd even for files outside of "/PS3_GAME/USRDIR".

[Megamouse]

main dir can be moved to most inner scope

[Augusto7743]

I not understand if all above is related with eboot.bin.
I has ISO being mounted in virtual drive being possible read copy files without issues.
In Windows mounting create a virtual drive and using command button OPEN in mounted virtual drive path work perfectly. The eboot is compiled and load the game. Gameplay is exactly the same how loading the game in dev_hdd0/disc/
In Linux the same command above not work. RPCS3 read and compile the eboot, but in next task being load the game close the load game window returning to RPCS3 GUI.
I not understand if is RPCS3 issue or enabled any security setting in Linux.