OpenMP: Thresholding doesn't work
Test case:

```Nim
import sequtils

var x = toSeq(1..1000)

let ompsize = x.len
let ompthreshold = 800

for i in `||`(0, x.len - 1, "if(ompthreshold < ompsize)"):
  x[i] += 2

echo x[0]
```

C code generated:
```C
N_LIB_PRIVATE N_NIMCALL(void, NimMainModule)(void) {
{
	TFrame FR_; FR_.len = 0;
}
// ..................
	T7_ = (x_wFAR9b1Cy8ShaaTQG2FH9c7g ? x_wFAR9b1Cy8ShaaTQG2FH9c7g->Sup.len : 0);
	ompsize_89bqUwA9bOswTIcWIVyaG9cfw = T7_;
	ompthreshold_XaMtJe9ajIFJ9btvwMO3AaEw = ((NI) 800);
	T8_ = (x_wFAR9b1Cy8ShaaTQG2FH9c7g ? x_wFAR9b1Cy8ShaaTQG2FH9c7g->Sup.len : 0);
	#pragma omp parallel for if(ompthreshold < ompsize)
for (i = ((NI) 0); i <= (NI)(T8_ - ((NI) 1)); ++i)	{
		x_wFAR9b1Cy8ShaaTQG2FH9c7g->data[i] += ((NI) 2);
	}
	nimZeroMem((void*)T10_, sizeof(tyArray_nHXaesL0DJZHyVS07ARPRA));
	T10_[0] = nimIntToStr(x_wFAR9b1Cy8ShaaTQG2FH9c7g->data[((NI) 0)]);
	echoBinSafe(T10_, 1);
}
```

We need to interpolate the Nim symbols ompsize_89bqUwA9bOswTIcWIVyaG9cfw and ompthreshold_XaMtJe9ajIFJ9btvwMO3AaEw