Drop the custom I length modifier from snprintf custom implementation.

Extensions should rather use the ZEND_LONG_FMT, ZEND_ULONG_FMT and
ZEND_XLONG_FMT macros defined in php-src/Zend/zend_long.h

Closes GH-5089

Author: Girgias

UPGRADING.INTERNALS

@@ -80,6 +80,11 @@ PHP 8.0 INTERNALS UPGRADE NOTES
   j. compare_objects() handler was removed. Extensions should use compare() object
      handler instead and check if both arguments are objects and have the same
      compare handler, using ZEND_COMPARE_OBJECTS_FALLBACK() macro.
+     
+  k. The 'I' length modifier, used to denote 32 and 64bit integer from the custom
+     snprintf implementation has been removed.
+     Use the ZEND_LONG_FMT, ZEND_ULONG_FMT and ZEND_XLONG_FMT macros defined in
+     php-src/Zend/zend_long.h
 
 ========================
 2. Build system changes

main/snprintf.c

@@ -712,25 +712,6 @@ static int format_converter(register buffy * odp, const char *fmt, va_list ap) /
 					fmt++;
 					modifier = LM_LONG_DOUBLE;
 					break;
-				case 'I':
-					fmt++;
-#if SIZEOF_LONG_LONG
-					if (*fmt == '6' && *(fmt+1) == '4') {
-						fmt += 2;
-						modifier = LM_LONG_LONG;
-					} else
-#endif
-						if (*fmt == '3' && *(fmt+1) == '2') {
-							fmt += 2;
-							modifier = LM_LONG;
-						} else {
-#ifdef _WIN64
-							modifier = LM_LONG_LONG;
-#else
-							modifier = LM_LONG;
-#endif
-						}
-					break;
 				case 'l':
 					fmt++;
 #if SIZEOF_LONG_LONG