lldb: Make i386-*-freebsd expression work on JIT path

• Enable i386 ABI creation for freebsd
• Added an extra argument in ABISysV_i386::PrepareTrivialCall for mmap syscall
• Unlike linux, the last argument of mmap is actually 64-bit(off_t). This requires us to push an additional word for the higher order bits.
• Prior to this change, ktrace dump will show mmap failures due to invalid argument coming from the 6th mmap argument.

Submitted by: Karnajit Wangkhem
Differential Revision: https://reviews.llvm.org/D34776