FIxed GDC compilation (basic betterC WIP) and some improvements

-fixed issue with adding/removing entities inside events handling
-fixed EntityMeta.getComponent() (added check if component_id is valid)
-added function hasComponent to entity to check if component exists

demos/external/sources/mmutils/thread_pool.d

@@ -182,6 +182,12 @@ void instructionPause()
 
 			__builtin_ia32_pause();
 		}
+		else version(GNU)
+		{
+			import gcc.builtins;
+
+			__builtin_ia32_pause();
+		}
 		else version (DigitalMars)
 		{
 			asm
@@ -189,7 +195,6 @@ void instructionPause()
 				rep;
 				nop;
 			}
-
 		}
 		else
 		{

demos/source/demos/snake.d

@@ -17,7 +17,7 @@ import ecs_utils.gfx.texture;
 import ecs_utils.math.vector;
 import ecs_utils.utils;
 
-import std.array : staticArray;
+//import std.array : staticArray;
 
 enum float px = 1.0/512.0;
 

demos/utils/source/ecs_utils/utils.d

@@ -21,7 +21,19 @@ float randomRangef(float min, float max)
 	return rand()%4096;
 }*/
 
-extern(C) int printf(scope const char* format, ...) @nogc nothrow @system;
+version(GNU)
+{
+	public import core.stdc.stdio : printf;
+	pragma(inline, true) T[n] staticArray(T, size_t n)(auto ref T[n] a)
+	{
+		return a;
+	}
+}
+else
+{
+	extern(C) int printf(scope const char* format, ...) @nogc nothrow @system;
+	public import std.array : staticArray;
+}
 extern(C) int rand();
 
 version(D_BetterC)