Don't use roundEven() to implement round() in DX9 compatibility mode

Test/baseResults/hlsl.round.dx10.frag.out

@@ -0,0 +1,60 @@
+hlsl.round.dx10.frag
+Shader version: 500
+gl_FragCoord origin is upper left
+0:? Sequence
+0:2  Function Definition: PixelShaderFunction(vf4; ( temp 4-component vector of float)
+0:2    Function Parameters: 
+0:2      'input' ( in 4-component vector of float)
+0:?     Sequence
+0:3      Branch: Return with expression
+0:3        roundEven ( temp 4-component vector of float)
+0:3          'input' ( in 4-component vector of float)
+0:?   Linker Objects
+
+
+Linked fragment stage:
+
+WARNING: Linking fragment stage: Entry point not found
+
+Shader version: 500
+gl_FragCoord origin is upper left
+0:? Sequence
+0:2  Function Definition: PixelShaderFunction(vf4; ( temp 4-component vector of float)
+0:2    Function Parameters: 
+0:2      'input' ( in 4-component vector of float)
+0:?     Sequence
+0:3      Branch: Return with expression
+0:3        roundEven ( temp 4-component vector of float)
+0:3          'input' ( in 4-component vector of float)
+0:?   Linker Objects
+
+// Module Version 10000
+// Generated by (magic number): 8000a
+// Id's are bound by 17
+
+                              Capability Shader
+               1:             ExtInstImport  "GLSL.std.450"
+                              MemoryModel Logical GLSL450
+                              EntryPoint Fragment 4  "main"
+                              ExecutionMode 4 OriginUpperLeft
+                              Source HLSL 500
+                              Name 4  "main"
+                              Name 11  "PixelShaderFunction(vf4;"
+                              Name 10  "input"
+               2:             TypeVoid
+               3:             TypeFunction 2
+               6:             TypeFloat 32
+               7:             TypeVector 6(float) 4
+               8:             TypePointer Function 7(fvec4)
+               9:             TypeFunction 7(fvec4) 8(ptr)
+         4(main):           2 Function None 3
+               5:             Label
+                              Return
+                              FunctionEnd
+11(PixelShaderFunction(vf4;):    7(fvec4) Function None 9
+       10(input):      8(ptr) FunctionParameter
+              12:             Label
+              13:    7(fvec4) Load 10(input)
+              14:    7(fvec4) ExtInst 1(GLSL.std.450) 2(RoundEven) 13
+                              ReturnValue 14
+                              FunctionEnd