Fix sampler usage

Patch from Nicolas at Transgaming.

src/OpenGL ES 2.0/compiler/OutputASM.cpp

diff --git a/src/OpenGL ES 2.0/compiler/OutputASM.cpp b/src/OpenGL ES 2.0/compiler/OutputASM.cpp
index 49a1262..b63f3ad 100644
--- a/src/OpenGL ES 2.0/compiler/OutputASM.cpp
+++ b/src/OpenGL ES 2.0/compiler/OutputASM.cpp
@@ -1911,7 +1911,7 @@
 
 				for(int i = 0; i < sampler->totalRegisterCount(); i++)
 				{
-					shader->declareSampler(i);
+					shader->declareSampler(index + i);
 				}
 			}