[PM]

The compiler is in "no sse" mode (which makes sense because enabling sse reduces the number of computers your code will run on - though nowadays eveyone has it and valve requires it AFAIK)

Looks like you will want to compile with the flags from the linux Makefiles of the AM HL2 projects, ie. at least

-mfpmath=sse -msse -DHAVE_STDINT_H -m32
(the last being 32 bit build even if you're on x64 -- though maybe Code::Blocks does that for you)

and maybe also
-fno-exceptions -fno-rtti

and stuff. Look at the Makefile of sourcemod / mm:s / etc., search for CFLAGS and CPPFLAGS.

Greetings,
PM