GPU/ShaderGen: Move discard to end of shader

Possible workaround for this PowerVR driver issue.

src/core/gpu_hw_shadergen.cpp

@@ -931,10 +931,6 @@ float4 SampleFromVRAM(uint4 texpage, float2 coords)
     // Apply semitransparency. If not a semitransparent texel, destination alpha is ignored.
     if (semitransparent)
     {
-      #if TRANSPARENCY_ONLY_OPAQUE
-        discard;
-      #endif
-
       #if USE_DUAL_SOURCE
         o_col0 = float4(color, oalpha);
         o_col1 = float4(0.0, 0.0, 0.0, u_dst_alpha_factor / ialpha);
@@ -945,13 +941,13 @@ float4 SampleFromVRAM(uint4 texpage, float2 coords)
       #if !PGXP_DEPTH
         o_depth = oalpha * v_pos.z;
       #endif
+
+      #if TRANSPARENCY_ONLY_OPAQUE
+        discard;
+      #endif
     }
     else
     {
-      #if TRANSPARENCY_ONLY_TRANSPARENT
-        discard;
-      #endif
-
       #if USE_DUAL_SOURCE
         o_col0 = float4(color, oalpha);
         o_col1 = float4(0.0, 0.0, 0.0, 1.0 - ialpha);
@@ -962,6 +958,10 @@ float4 SampleFromVRAM(uint4 texpage, float2 coords)
       #if !PGXP_DEPTH
         o_depth = oalpha * v_pos.z;
       #endif
+
+      #if TRANSPARENCY_ONLY_TRANSPARENT
+        discard;
+      #endif
     }
   #else
     // Non-transparency won't enable blending so we can write the mask here regardless.

src/core/shader_cache_version.h

@@ -1,4 +1,4 @@
 #pragma once
 #include "types.h"
 
-static constexpr u32 SHADER_CACHE_VERSION = 3;
+static constexpr u32 SHADER_CACHE_VERSION = 4;