bug: fix crash on Apple platforms (lvgl#13)

For some obscure reason, `_NSGetExecutablePath(char* buf, uint32_t* bufsize)`
writes `bufsize + 1` characters into `buf`, hence we are allocating the buffer as
`PATH_MAX + 1`.

src/utils/utils.c

@@ -1,7 +1,7 @@
 #include "utils.h"
 
 void GetProgramDir (char* buf) {
-    char str[PATH_MAX];
+  char str[PATH_MAX + 1];
 	char* dir;
 
 	#ifdef __APPLE__
@@ -111,4 +111,4 @@ void ReplenishExt (char* path) {
     if (ext[0] == '\0') {
         strcat(path, ".js");
     }
-}
+}