ReflectionClass::isCloneable(): reduce duplication

[DanielEScherzer]

When the zend_class_entry has a zend_function entry for clone, the logic is the same regardless of if the reflection_object entry has an object or not; the determination is based solely on the flags of the zend_function.

[DanielEScherzer]

Test failure appears unrelated:

NMAKE : fatal error U1077: '  "C:\obj\Release_TS\php.exe" -d open_basedir= -d output_buffering=0 run-tests.php -d opcache.enable=1 -d opcache.enable_cli=1 -d opcache.protect_memory=1 -d opcache.jit_buffer_size=64M -d opcache.jit=tracing -g FAIL,BORK,LEAK,XLEAK  --no-progress -q --offline --show-diff --show-slow 1000 --set-timeout 120 --temp-source c:\tests_tmp --temp-target c:\tests_tmp -j2 -p "C:\obj\Release_TS\php.exe"' : return code '0x1'

[iluuu1994]

Thank you @DanielEScherzer!