Fix breakage of DSO loading on all platforms

Summary: bc00a9937 fixed a spelling error, but failed to fix the accidentally inverted logic, meaning that instead of underscores being unconditionally omitted, they would instead be added when they are not needed, and omitted when they are needed.

Exit statuses are hard. Used EXIT_SUCCESS/EXIT_FAILURE in the hopes of making the code readable.
Closes #3104

Reviewed By: @paroski

Differential Revision: D1419880

Pulled By: @jwatzman
Use default syntax in _php_mb_regex_ereg_search_exec

Summary: `_php_mb_regex_ereg_search_exec` was using an invalid syntax (`NULL`) and that ended up with a segfault whenever it was used.
Fixes #3111

Reviewed By: @ptarjan

Differential Revision: D1420000
Link libzip from where it's found, not from unspecified

Summary: Passing the full path to the target lib ensures the
right linker flag is set.

Reviewed By: @ptarjan

Differential Revision: D1418348
Expose APC info to admin port and via apc_cache_info() to give open source too a visibility over APC

Summary: expose APC info via apc_cache_info and admin port

Reviewed By: @markw65

Differential Revision: D1405003