wgl: strings.h does not exist in MSVC
wgl: strings.h does not exist in MSVC

Slipped out when rebasing/clearing up the MSVC fixes. The build succeeds
with mingw-w64 (gcc) so it went unnoticed.

Signed-off-by: Emil Velikov <4c996f2f093ddd0585a556460b4cc3ba555546ef@gmail.com>
Reviewed-by: Chad Versace <a557f7f75bf28dc19ac99107f5cc7cd6b3fbdb1a@linux.intel.com>

dcbaker/waffle,dcbaker/waffle,fjhenigman/waffle,chadversary/waffle,waffle-gl/waffle,fjhenigman/waffle,maurossi/waffle,evelikov/waffle,waffle-gl/waffle,evelikov/waffle,evelikov/waffle,fjhenigman/waffle,chadversary/waffle,dcbaker/waffle,maurossi/waffle,waffle-gl/waffle,waffle-gl/waffle,maurossi/waffle,chadversary/waffle