Speed up GCC compilation in Github workflow with '-jnproc' parameter

Author: Lethja

.github/workflows/LuaWatcom.yml

@@ -29,7 +29,7 @@ jobs:
     - name: Check GCC can build Lua after patches
       run: |
         cd lua
-        make
+        make -j`nproc`
         cd ..
 
     - name: Build Lua for DOS 16-bit