Disables executable support and improve shared library loading

Disables the ability to load executables (ET_EXEC) until the OS
supports userland applications.

Additionaly, improve the shared library loading with support for
PIC and non-PIC binaries and also performing relocations (R_386_32,
R_386_JMP_SLOT, R_386_GLOB_DAT, R_386_PC32 and R_386_RELATIVE).