Fix for compilation problem again

[david-puglielli]

This change is 

[coveralls]

Coverage decreased (-0.04%) to 75.148% when pulling 0b15997 on david-puglielli:string-initialisation-nulls into d699680 on Microsoft:dev.

[codecov-io]

Codecov Report

Merging #827 into dev will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##              dev     #827   +/-   ##
=======================================
  Coverage   80.06%   80.06%           
=======================================
  Files          25       25           
  Lines        7323     7323           
=======================================
  Hits         5863     5863           
  Misses       1460     1460

Impacted Files	Coverage Δ
...c14/x86/php-7.1.20-src/ext/pdo_sqlsrv/pdo_stmt.cpp	86.15% <0%> (ø)	⬆️

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