SPV Version: Emit the requested SPIR-V version, not the header version.

Fixes #1236.

Test/baseResults/hlsl.rw.bracket.frag.out

@@ -1743,7 +1743,7 @@ gl_FragCoord origin is upper left
 0:?     'anon@0' (layout( row_major std140) uniform block{ uniform int c1,  uniform 2-component vector of int c2,  uniform 3-component vector of int c3,  uniform 4-component vector of int c4,  uniform int o1,  uniform 2-component vector of int o2,  uniform 3-component vector of int o3,  uniform 4-component vector of int o4,  uniform 4-component vector of float uf4,  uniform 4-component vector of int ui4,  uniform 4-component vector of uint uu4})
 0:?     '@entryPointOutput.Color' (layout( location=0) out 4-component vector of float)
 
-// Module Version 10200
+// Module Version 10000
 // Generated by (magic number): 80003
 // Id's are bound by 607