Fix incorrect page_size check

The current check always evaluated to false because if `!page_size`
is true, then `page_size & (page_size - 1)` equals `0 & (0 - 1)` which
is always 0. The if condition is meant to check if page_size is zero or
not a power of two, thus we must change the AND to an OR to fix this
issue.

Closes GH-10427

Signed-off-by: George Peter Banyard <[email protected]>

Author: nielsdos

NEWS

@@ -9,6 +9,9 @@ PHP                                                                        NEWS
 - FFI:
   . Fixed incorrect bitshifting and masking in ffi bitfield. (nielsdos)
 
+- Opcache:
+  . Fix incorrect page_size check. (nielsdos)
+
 - Standard:
   . Fixed bug GH-10292 (Made the default value of the first param of srand() and
     mt_srand() unknown). (kocsismate)

ext/opcache/ZendAccelerator.c

@@ -3197,7 +3197,7 @@ static zend_result accel_post_startup(void)
 			size_t page_size;
 
 			page_size = zend_get_page_size();
-			if (!page_size && (page_size & (page_size - 1))) {
+			if (!page_size || (page_size & (page_size - 1))) {
 				zend_accel_error_noreturn(ACCEL_LOG_FATAL, "Failure to initialize shared memory structures - can't get page size.");
 				abort();
 			}