Fix a crash bug.
Add a switch type parameter to BuildAll Powershell script which makes
it possible to build the installers after building drivers.
Add msvc runtime dlls which are needed by the drivers to the installers.
Improve pgxalib.dll(MSDTC support).
1. Change xa_open() so that it tries to connect to the database immediately.
   This would cause an error at enlistment in dtc when the authentication
   method depends not only on the db user but also on the OS user and it
   means the automatic transaction recovery is unavailable.
2. Log the error message in case of SQLDriverConnect() error.
3. Improve the logging.