__attribute__ ((constructor)) question

[Stephen Smith]

The following code is a code fragment from a program of mine.   test_constructor() isn't
being run.  I thought that test_constructor() was supposed to run before main.  It used to work in
2.8.1 on my system.

target=powerpc-motorola-elf.

Any clue?

int testvalue = 0;

// Why doesn't this constructor work?
void test_constructor(void)   __attribute__ ((constructor));

void test_constructor(void)
{
    testvalue = 1;
}

main()
{

    // some piece of code using testvalue and expecting it to be one.
}