refac: replace vector into map

[minseoc03]

Resolves #2

Summary

This PR refactors the core date structures in llvm-block to improve performance and memory usage.

• Replace the std::vector<collist*> table with TableMap = std::unordered_map<int, collist*> (keyed by line number).
• Replace the std::list<col*>cols inside collist with `std::unordered_map<int, col*> (keyed by column number)
• Update all lookup sites (CreateTable, InsertTable, CompareLR) to use fast map.find() instead of linear scans or repeated resize().

Motivation

• Sparse line numbers are common after optimization or macro expansion; the old vector approach wasted memory and spent time resizing.
• std::list lookups in searchcol() were O(n) in the number of columns; switching to unordered_map yields amortized O(1) lookups.

What's Changed

llvm-block.cpp

• Swapped std::vector<collist*> table for using TableMap = std::unordered_map<int, collist*>
• Replaced every table.at(line) + resize() pattern with table.find(line) + insert-if-missing.
• Updated CreateTable(), InsertTable(), and CompareLR() to use the new map.

table.h/table.cpp

• Changed collist::cols from std::list<col*> to std::unordered_map<int, col*>
• Rewrote push(col*) and searchcol(int) to use cols.find() for O(1) insert / lookup.

[eomiso]

Hi @minseoc03,
The code review for this PR is taking a bit longer than usual due to some other priorities currently in progress.
I'm planning to merge this after I complete a bit of refactoring on the llvm-flow project (which depends on llvm-block), along with adding some test coverage.