Description:
------------
Currently, HANDLE_BLOCK_INTERRUPTIONS and HANDLE_UNBLOCK_INTERRUPTIONS are used  either for ZEND_SIGNAL support, or to call out to the zend utility functions struct to call a SAPI-specific function.

However, the only SAPIs that populates those functions in the utility struct are the obsolete Apache 1 SAPIs: in all other cases the function pointer is NULL. As such, when ZEND_SIGNAL is off, we can actually remove the conditional branch entirely.
    
This leads to a speed up on PHP5 code. I've measured the performance
impact on a PowerPC 64-bit little-endian system and on a x86_64 laptop
using the test script below.    

I see a ~6% improvement in performance on POWER and a ~4% improvement
on x86_64.
    
I also see an improvement in a e-commerce web application on POWER
with this change.

I've submitted this change as a pull request on GitHub.

Test script:
---------------
    <?php
    for ($i=1; $i < 100000000; $i++) {
            $genericObject = new stdClass();
            $a = (object) 8;
            $b = (object) 'abcde';
    }
    ?>