Fix FEAT-39125
Add EMU_ENV option. If it is ON, the building is for
emulation environment, thus some logics can be adjusted
to match emulation environment. If it is OFF, the
building is for regular environment.
Currently only ocltst will use the option. But it can
be used for other modules.
Change-Id: I54e1bc1309e82794b41fca2ae1f01f004138dced
taosang2
76c6dcd558