Yes, it does. Using these macros everywhere makes the code more opaque, thus less legible, and therefore less secure.
Is this 2014 or 1994? My IDE automatically colors out dead sections where preprocessor macros don't apply to me. Honestly if you are unable to understand or mentally deal with a few preprocessor macro's I don't want you anywhere near openSSL.
They are hardly "everywhere" mostly in the headers and abstraction layers which provide a common target and normalized behavior for supported platforms.
"Many eyes" can't make all bugs shallow if those eyes don't understand what the hell they are looking at.
If eyes stumble on a few preprocessor definitions the chance of them discovering anything useful in this project is zero. I'm all for making shit easier to understand but this specific kind of "premature optimization" accomplishes nothing.
#ifdef VMS
#define SOMEFUNC(x,y,z) SomeVmsFunc (z,y,x)
#else
#define SOMEFUNC(x,y,z) TotallyOtherFunc (x,y,z)
#endif
You don't see how that fucks up the legibility of code? You encounter SOMEFUNC(1,2,3); and you have no idea what it does and your damn IDE can't colour-code that away either.