aaudio: prevent out-of-bounds read in resampler

The cursor was initialized to -1 instead of 0.
Now it is set to 0.
This fixes a crash when running with HWASAN.

The mInputCallCount is now initialized to kInitialCounter.
See https://github.com/google/oboe/issues/987
for more info and a regression test.

Bug: 336391852
Test: Flash a HWASAN build then
Test: atest CtsNativeMediaAAudioTestCases
Test: or see bug for steps using OboeTester
Flag: EXEMPT bugfix
Change-Id: Ifadaa94a755c77e4888d66009a8de7df4bce22bc