use a constant for the mod dir buffer size

include/stk.h

@@ -4,6 +4,8 @@
 #include "stk_version.h"
 #include <stdlib.h>
 
+#define MOD_DIR_BUFFER_SIZE 32
+
 #ifdef __cplusplus
 extern "C" {
 #endif

src/module.c

@@ -7,7 +7,7 @@ void *platform_get_symbol(void *handle, const char *symbol);
 
 typedef void (*stk_module_func)(void);
 
-char *stk_mod_dir = NULL;
+char stk_mod_dir[MOD_DIR_BUFFER_SIZE];
 static void **stk_handles = NULL;
 static stk_module_func *stk_inits = NULL;
 static stk_module_func *stk_shutdowns = NULL;

src/stk.c

@@ -1,7 +1,7 @@
 #include "stk.h"
 #include "stk_log.h"
 
-extern char *stk_mod_dir;
+extern char stk_mod_dir[MOD_DIR_BUFFER_SIZE];
 
 int stk_init(const char *mod_dir)
 {