Replace remaining PHP errors with PHP exceptions

`SWIG_ErrorCode()`, `SWIG_ErrorMsg()`, `SWIG_FAIL()` and `goto thrown;`
are no longer supported (these are really all internal implementation
details and none are documented aside from brief mentions in CHANGES
for the first three).  I wasn't able to find any uses at least in FOSS
code via code search tools.

If you are using these:

Use `SWIG_PHP_Error(code,msg);` instead of `SWIG_ErrorCode(code);
SWIG_ErrorMsg(msg);` (which will throw a PHP exception in SWIG >= 4.1
and do the same as the individual calls in older SWIG).

`SWIG_FAIL();` and `goto thrown;` can typically be replaced with
`SWIG_fail;`.  This will probably also work with older SWIG, but
please test with your wrappers if this is important to you.

Fixes #2014

Lib/exception.i

@@ -25,7 +25,7 @@
     code == SWIG_DivisionByZero ? zend_ce_division_by_zero_error : \
     code == SWIG_SyntaxError ? zend_ce_parse_error : \
     code == SWIG_OverflowError ? zend_ce_arithmetic_error : \
-    NULL, msg, code); goto thrown; } while (0)
+    NULL, msg, code); SWIG_fail; } while (0)
 %}
 #endif