build: Fix strndup detection on MinGW

GCC and meson conspire together to incorrectly detect that strndup()
exists on MinGW as __builtin_strndup, when no such function exists. As a
work around, meson will skip looking for __builtin functions if an
'#include' is in the prefix, so add '#include <string.h>' when looking
for strndup().


Signed-off-by: Joshua Watt <>
2 jobs for mingw-fixes in 2 minutes and 2 seconds