multiply_frac wrong overflow

[mdionisio]

I'm doing an asrc. I have problem because multiply_frac wrongly go in overflow.

My case is
in rate: 48000
out rate: 48000
num_rate: 500733
den_rate: 500000
num/den = 1.001466

and for example my samp_frac_num is 173475.

then I set
num_rate: 199999
den_rate: 1000000
num/den = 0.199999

this is a big change in ratio, but is done only to test.

When I do this change, I get overflow in multiply_frac function.

remain = 173475 > UINT32_MAX / 1000000 and this go in overflow.

but if I do all the operation with 64bit is ok
remain * num / den + major * num = 173475 * 199999 / 1000000 + 0 * 199999 = 34694 and this is correct.

the 2nd problem is that if multiply_frac fails wile I'm calling speex_resampler_set_rate_frac
the internal variable is left wrangly updated, and this create more problems later with possible access to invalid memory.