Fixed DStress tests nocompile/c/{const_32_B.d,const_32_C.d}. Updated the runtest script to build libtangobos-partial.a if it hasn't already been built. Added in signbit() and va_arg!()() to libtangobos-partial.a so more of the phobos dependent DStress tests pass.

module tangotests.ina1;

import tango.stdc.stdio;

void main()
{
    int alder;
    printf("Hvor gammel er du?\n");
    scanf("%d", &alder);
    printf("om 10 år er du %d\n", alder + 10);
}