check some system lib deps on Linux and force user to provide their own liblua54 from package managers

src/BizHawk.Client.EmuHawk/Program.cs

@@ -36,7 +36,30 @@ namespace BizHawk.Client.EmuHawk
 
 			if (OSTC.IsUnixHost)
 			{
-				// for Unix, skip everything else and just wire up the event handler
+				// for Unix, we'll check a few system libraries and wire up the event handler
+
+				foreach (var soToLoad in new[]
+				{
+					"libspeexdsp.so.1", // for old BSNES and melonDS (TODO: should we remove this dependency? old BSNES will be axed soon enough, BlipBuffer could probably work well enough for melonDS?)
+					"liblua54.so", // lua console (TODO: should we rather just disable lua console if this cannot be found?)
+					// there are some other dependencies, but mono will provide them anyways
+				})
+				{
+					var p = OSTC.LinkedLibManager.LoadOrZero(soToLoad);
+					if (p != IntPtr.Zero)
+					{
+						OSTC.LinkedLibManager.FreeByPtr(p);
+						continue;
+					}
+					// else it's missing or corrupted
+					using (ExceptionBox box = new($"EmuHawk needs {soToLoad} in order to run! You will need to install it via your distro's package manager. (EmuHawk will now close.) Internal error message: {OSTC.LinkedLibManager.GetErrorMessage()}"))
+					{
+						box.ShowDialog();
+					}
+					Process.GetCurrentProcess().Kill();
+					return;
+				}
+
 				AppDomain.CurrentDomain.AssemblyResolve += CurrentDomain_AssemblyResolve;
 				return;
 			}