switch to thread safe hash trie map

Initial implementation of the symbol table allowed us to push symbols
from one thread at a time and required a wonky lock-step and spread out
logic for replacing symbols. And because it was a externally chained
hash table we had to guesstimate optimal capacity for small and big targets.
We erred on the side of larger capacity to prevent degradation and
rehashing, however this meant small targets had to spent unreasonable
amount of time memory allocing slots. With hash trie we can dynamically
scale up to 4 ^ 32 items and atomically replace symbols when needed. Neat!

src/linker/lnk_lib.h

@@ -12,6 +12,7 @@ typedef struct LNK_Lib
   U32 *            member_off_arr;
   String8List      symbol_name_list;
   String8          long_names;
+  U64              input_idx;
 } LNK_Lib;
 
 typedef struct LNK_LibNode
@@ -92,9 +93,10 @@ typedef struct LNK_LibBuild
 
 typedef struct
 {
-  LNK_LibNode *node_arr;
-  String8     *data_arr;
-  String8     *path_arr;
+  LNK_LibNode     *node_arr;
+  String8         *data_arr;
+  String8         *path_arr;
+  U64              base_input_idx;
 } LNK_LibIniter;
 
 ////////////////////////////////