glsl: drop an useless min in FS

GPU will clamp color anyway. It reduces the number of instruction of 25% (4->3)

plugins/GSdx/res/glsl/merge.glsl

@@ -29,7 +29,8 @@ layout(binding = 0) uniform sampler2D TextureSampler;
 void ps_main0()
 {
     vec4 c = texture(TextureSampler, PSin_t);
-    c.a = min(c.a * 2.0, 1.0);
+    // Note: clamping will be done by fixed unit
+    c.a *= 2.0f;
     SV_Target0 = c;
 }
 

plugins/GSdx/res/glsl_source.h

@@ -515,7 +515,8 @@ static const char* merge_glsl =
 	"void ps_main0()\n"
 	"{\n"
 	"    vec4 c = texture(TextureSampler, PSin_t);\n"
-	"    c.a = min(c.a * 2.0, 1.0);\n"
+	"    // Note: clamping will be done by fixed unit\n"
+	"    c.a *= 2.0f;\n"
 	"    SV_Target0 = c;\n"
 	"}\n"
 	"\n"