Add target envs for OpenCL, OpenGL

Covers: OpenCL 2.1, OpenCL 2.2
Covers: OpenGL 4.0, OpenGL 4.1, OpenGL 4.2, OpenGL 4.3, OpenGL 4.5.
The OpenGL environments assume the use of GL_ARB_gl_spirv, of course.
diff --git a/source/opcode.cpp b/source/opcode.cpp
index 22a0df6..2e6c7da 100644
--- a/source/opcode.cpp
+++ b/source/opcode.cpp
@@ -101,9 +101,16 @@
   switch (env) {
     case SPV_ENV_UNIVERSAL_1_0:
     case SPV_ENV_VULKAN_1_0:
+    case SPV_ENV_OPENCL_2_1:
+    case SPV_ENV_OPENGL_4_0:
+    case SPV_ENV_OPENGL_4_1:
+    case SPV_ENV_OPENGL_4_2:
+    case SPV_ENV_OPENGL_4_3:
+    case SPV_ENV_OPENGL_4_5:
       *pInstTable = &table_1_0;
       return SPV_SUCCESS;
     case SPV_ENV_UNIVERSAL_1_1:
+    case SPV_ENV_OPENCL_2_2:
       *pInstTable = &table_1_1;
       return SPV_SUCCESS;
   }