backport php 8 support from upstream
https://github.com/swig/swig/pull/1978 via
https://src.fedoraproject.org/rpms/swig/c/62dded8bacb09398b03d1352820636182d2494ab

Index: Lib/cdata.i
--- Lib/cdata.i.orig
+++ Lib/cdata.i
@@ -21,7 +21,7 @@ typedef struct SWIGCDATA {
 }
 %typemap(in) (const void *indata, int inlen) = (char *STRING, int LENGTH);
 
-#elif SWIGPHP7
+#elif SWIGPHP
 
 %typemap(out) SWIGCDATA {
   ZVAL_STRINGL($result, $1.data, $1.len);
