Fix macOS PowerPC build.
https://www.freelists.org/post/luajit/LuaJIT-on-OS-X-Leopard-PowerPC,1
--- src/host/buildvm.c.orig	2022-03-13 12:34:59.000000000 -0500
+++ src/host/buildvm.c	2022-03-19 15:42:34.000000000 -0500
@@ -113,7 +113,7 @@
       name[0] = name[1] == 'R' ? '_' : '@';  /* Just for _RtlUnwind@16. */
     else
       *p = '\0';
-#elif LJ_TARGET_PPC && !LJ_TARGET_CONSOLE
+#elif LJ_TARGET_PPC && !LJ_TARGET_CONSOLE && !LJ_TARGET_OSX
     /* Keep @plt etc. */
 #else
     *p = '\0';