luajit contains full support for lightuserdata on aarch64 in newest 2.1 versions

Issue: #3459

This disables a workaround only intended for aarch64 if the target
architecture is powerpc.

Issue: #3365

[74/340] Building C object contrib/lua-lpeg/CMakeFiles/rspamd-lpeg.dir/lpprint.c.o
In file included from ../contrib/lua-lpeg/lpprint.c:11:
../contrib/lua-lpeg/lptypes.h:15: warning: "NDEBUG" redefined
   15 | #define NDEBUG
      |
<command-line>: note: this is the location of the previous definition
[75/340] Building C object contrib/lua-lpeg/CMakeFiles/rspamd-lpeg.dir/lpcap.c.o
In file included from ../contrib/lua-lpeg/lpcap.h:9,
                 from ../contrib/lua-lpeg/lpcap.c:9:
../contrib/lua-lpeg/lptypes.h:15: warning: "NDEBUG" redefined
   15 | #define NDEBUG
      |
<command-line>: note: this is the location of the previous definition
[77/340] Building C object contrib/lua-lpeg/CMakeFiles/rspamd-lpeg.dir/lpvm.c.o
In file included from ../contrib/lua-lpeg/lpcap.h:9,
                 from ../contrib/lua-lpeg/lpvm.c:15:
../contrib/lua-lpeg/lptypes.h:15: warning: "NDEBUG" redefined
   15 | #define NDEBUG
      |
<command-line>: note: this is the location of the previous definition
[79/340] Building C object contrib/lua-lpeg/CMakeFiles/rspamd-lpeg.dir/lpcode.c.o
In file included from ../contrib/lua-lpeg/lpcode.c:12:
../contrib/lua-lpeg/lptypes.h:15: warning: "NDEBUG" redefined
   15 | #define NDEBUG
      |
<command-line>: note: this is the location of the previous definition
[81/340] Building C object contrib/lua-lpeg/CMakeFiles/rspamd-lpeg.dir/lptree.c.o
In file included from ../contrib/lua-lpeg/lptree.c:15:
../contrib/lua-lpeg/lptypes.h:15: warning: "NDEBUG" redefined
   15 | #define NDEBUG
      |
<command-line>: note: this is the location of the previous definition

Issue: #2906