Allow variables in modular_gc_dir

Such as `$(ruby_version)`, `$(arch)` and so on.

1 files changed, 1 insertions, 0 deletions

diff --git a/gc.c b/gc.c
index 19e65a1f14..67857ed44c 100644
--- a/gc.c
+++ b/gc.c
@@ -707,6 +707,7 @@ typedef struct gc_function_map {
 static rb_gc_function_map_t rb_gc_functions;
 
 # define RUBY_GC_LIBRARY "RUBY_GC_LIBRARY"
+# define MODULAR_GC_DIR STRINGIZE(modular_gc_dir)
 
 static void
 ruby_modular_gc_init(void)