Fix unreachable code in getSampledType()

Fixed #2763
diff --git a/SPIRV/GlslangToSpv.cpp b/SPIRV/GlslangToSpv.cpp
index 71b00d7..421e650 100644
--- a/SPIRV/GlslangToSpv.cpp
+++ b/SPIRV/GlslangToSpv.cpp
@@ -3940,12 +3940,14 @@
             builder.addExtension(spv::E_SPV_AMD_gpu_shader_half_float_fetch);
             builder.addCapability(spv::CapabilityFloat16ImageAMD);
             return builder.makeFloatType(16);
-        case glslang::EbtInt64:      return builder.makeIntType(64);
+        case glslang::EbtInt64:
             builder.addExtension(spv::E_SPV_EXT_shader_image_int64);
-            builder.addCapability(spv::CapabilityFloat16ImageAMD);
-        case glslang::EbtUint64:     return builder.makeUintType(64);
+            builder.addCapability(spv::CapabilityInt64ImageEXT);
+            return builder.makeIntType(64);
+        case glslang::EbtUint64:
             builder.addExtension(spv::E_SPV_EXT_shader_image_int64);
-            builder.addCapability(spv::CapabilityFloat16ImageAMD);
+            builder.addCapability(spv::CapabilityInt64ImageEXT);
+            return builder.makeUintType(64);
 #endif
         default:
             assert(0);