For cygwin, using the PSDK headers:

#define _STDCALL_SUPPORTED, _M_IX86, _inline=__inline__
-Wno-unknown-pragmas
But then there is all the __asm, which won't work with GCC. :-(

---Hexen---

Pig (not player) needs MF3_SEEISALSOACTIVE and activesound "PigActive2"

MT_WRAITHB, MT_SERPENT, MT_SERPENTLEADER, and MT_MINOTAUR need MF3_STAYMORPHED
MT_LEAF1, MT_LEAF2, MT_SPLASH and MT_SLUDGECHUNK need MF3_DONTSPLASH
MT_CENTAUR_FX is launched at z+45*FRACUNIT
MT_ICEGUY_FX is launched at z+40*FRACUNIT
MT_HOLY_MISSILE is launched at z+40*FRACUNIT
MT_ICEGUY_FX2 is launched at z+3*FRACUNIT
MT_MSTAFF_FX2 is launched at z+40*FRACUNIT
MT_LIGHTNING_FLOOR is launched at ONFLOORZ
MT_LIGHTNING_CEILING is launched at ONCEILINGZ
MT_MWAND_MISSILE and MT_CFLAME_MISSILE need MF3_VERYFAST

Anything with MF2_BOSS also needs MF3_IGNOREMATTACKS