In the file Zend/zend_API.c _array_init and some other functions are declared as inline.  Within the zend_API.h file some of the inlines are sort of "aliased" away making them non-inlined functions.

#define array_init(arg)                 _array_init((arg) ZEND_FILE_LINE_CC)
#define object_init(arg)                _object_init((arg) ZEND_FILE_LINE_CC)
#define object_init_ex(arg, ce) _object_init_ex((arg), (ce) ZEND_FILE_LINE_CC)
ZEND_API int _array_init(zval *arg ZEND_FILE_LINE_DC);
ZEND_API int _object_init(zval *arg ZEND_FILE_LINE_DC);
ZEND_API int _object_init_ex(zval *arg, zend_class_entry *ce ZEND_FILE_LINE_DC);

Since these functions are declared inline in the zend_API.c file no global symbol is
made.  These functions should be either be put in the header file or not declared as inlined.  As a result, on IRIX, php is created missing these global symbols.

I do not have a complete list of symbols as of yet.  Please feel free to contact me for more information.