Convert::NativeToInt64 with SUPPORT_ANY_BASE_CONVERSION delivers incorrect results

[MatthiasJentsch]

Details about Problem

nanoFramework area: nanoCLR preview 1010 / mscorlib perview 73

Worked before? No

Detailed repro steps so we can see the same problem

It's reproducible with all firmware that was compiled with SUPPORT_ANY_BASE_CONVERSION=ON.

E.g. Convert.ToInt16("1011110101001010", 2) should return -17078 because the MSB is set. But that return 0. It's caused by the native call to Convert::NativeToInt64. We shouldn't convert the 16bit base 2 string via strtoll. That results in the value 48458. After the check (result > maxValue || result < minValue) ? zero : result NativeToInt64 returns 0.
We have the same issue with ToInt32 and ToSByte.

With ToInt64 we have another issue:

long x1 = Convert.ToInt64("1100001001001011001001010101001100100000011011011111111111110011", 2);
long x2 = Convert.ToInt64("1411131125144033377763", 8);
long x3 = Convert.ToInt64("-4446419168141639693");
long x4 = Convert.ToInt64("C24B2553206DFFF3", 16);

All x values should be -4446419168141639693. But only x3 has this value. The other values are 9223372036854775807 which is not correct.

And last issue is Convert.ToUInt64 which is implemented in mscorlib with this call: return (ulong)NativeToInt64(value, true, 0, 0, fromBase);. Min and max value are set to 0 and second parameter signals a signed conversion. That can't work.