Buffer overrun in httpclient.c - _CreateHttpHeader

[dantraMSFT]

The logic that calculates the buffer size does not take into account the trailing \r\n. In cases where 10 digit value consumes 9 or 10 characters, the buffer is overrun.

The fix is to add an extra call to SizeTAdd; something like the following

SizeTAdd(pageSize, 2, &pageSize) != S_OK

This is blocking the release of the PSRP package and repros consistently in PowerShell 6 when creating a new session to office 365.

See issue PowerShell/PowerShell#5130