relax the full profile fp16 tan accuracy requirement to 2.5 ULP (KhronosGroup#1387)

* relax the full profile fp16 tan accuracy requirement to 2.25 ULP

The embedded profile accuracy requirement is unchanged and remains
3 ULP.

* further relax the fp16 tan accuracy requirement to 2.5 ULP

Author: bashbaug

OpenCL_C.txt

@@ -16441,7 +16441,7 @@ is the infinitely precise result.
 | *smoothstep*  | Implementation-defined        | Implementation-defined
 | *sqrt*        | \<= 1.5 ulp                   | \<= 1.5 ulp
 | *step*        | 0 ulp                         | 0 ulp
-| *tan*         | \<= 2 ulp                     | \<= 3 ulp
+| *tan*         | \<= 2.5 ulp                   | \<= 3 ulp
 | *tanh*        | \<= 2 ulp                     | \<= 3 ulp
 | *tanpi*       | \<= 2 ulp                     | \<= 3 ulp
 | *tgamma*      | \<= 4 ulp                     | \<= 4 ulp

env/numerical_compliance.asciidoc

@@ -596,7 +596,7 @@ given as ULP values for the full profile.
 | *OpExtInst* *tan*
 | \<= 5 ulp
 | \<= 5 ulp
-| \<= 2 ulp
+| \<= 2.5 ulp
 
 | *OpExtInst* *tanh*
 | \<= 5 ulp