Revert "Reference platform.h by ../src/platform.h - AIX is ignoring -I flags"

This reverts commit 015d9564ee16959847a30a0ec3b080f718f40678.
Merge pull request #677 from vortechs2000/fix_aix

Revert "Reference platform.h by ../src/platform.h - AIX is ignoring -I flags"