libpci: For MSVC < 19.00 define snprintf outside of endian section

libpci: For MSVC < 19.00 define snprintf outside of endian section

snprintf() macro is not endian specific and therefore should be declared
outside of the endian section.

This also fixes snprintf() function for new MinGW-w64 toolchains where
snprintf() is defined as wrapper around _snprintf() which do not return
negative value on overflow. libpci would call MinGW-w64 patched snprintf()
function and not broken system function _snprintf().