mesa: Mark GetBufferParameteri64v as implemented.

Apparently this was accidentally marked as unimplemented, and thus not
put in the dispatch table.

Fixes 7 es3conform tests:
- copy_buffer_parameters
- copy_buffer_data
- copy_buffer_usage
- pixel_buffer_object_bind
- pixel_buffer_object_parameteriv
- pixel_buffer_object_texture_read
- pixel_buffer_object_usage

v2: Also update the DispatchSanity test for this change.

Reviewed-by: Matt Turner <mattst88@gmail.com>

src/mapi/glapi/gen/GL3x.xml

@@ -601,8 +601,7 @@
     <param name="data" type="GLint64 *"/>
   </function>
 
-  <function name="GetBufferParameteri64v" offset="assign" es2="3.0"
-            exec="skip">
+  <function name="GetBufferParameteri64v" offset="assign" es2="3.0">
     <param name="target" type="GLenum"/>
     <param name="pname" type="GLenum"/>
     <param name="params" type="GLint64 *"/>

src/mesa/main/tests/dispatch_sanity.cpp

@@ -1301,8 +1301,7 @@ const struct function gles3_functions_possible[] = {
    { "glGetActiveUniformBlockiv", 30, -1 },
    { "glGetActiveUniformBlockName", 30, -1 },
    { "glGetActiveUniformsiv", 30, -1 },
-   // We have an implementation (added Jan 1 2010, 1fbc7193) but never tested...
-   // { "glGetBufferParameteri64v", 30, -1 },
+   { "glGetBufferParameteri64v", 30, -1 },
    // We check for the aliased -OES version in GLES 2
    // { "glGetBufferPointerv", 30, -1 },
    { "glGetFragDataLocation", 30, -1 },