fix possibly uninitialized value
Fixed bug #61645 (fopen and O_NONBLOCK)

if a mode like "rn" was passed to fopen(), then
php_stream_parse_fopen_modes() would assign O_WRONLY to
flags, because O_NONBLOCK tainted flags for the r/w/+ check
Replace invalid code with a proper #error

This code creates a nasty error as mentioned in bugs #31131, #37062
Patch taken from Debian's PHP package: 044-strtod_arm_fix