src: fix http2 debug build errors

Currently building with debug enabled produces the following errors:

In file included from ../src/node_http2.h:6:
../src/node_http2_core-inl.h:465:18: error: expected ';' after do/while
statement
  CHECK_GT(id, 0)
                 ^
                 ;
../src/node_http2_core-inl.h:469:18: error: use of undeclared identifier
'spec'
  OnPriority(id, spec.stream_id, spec.weight, spec.exclusive);
                 ^
../src/node_http2_core-inl.h:469:34: error: use of undeclared identifier
'spec'
  OnPriority(id, spec.stream_id, spec.weight, spec.exclusive);
                                 ^
../src/node_http2_core-inl.h:469:47: error: use of undeclared identifier
'spec'
  OnPriority(id, spec.stream_id, spec.weight, spec.exclusive);
                                              ^

This commit adds the missing semicolon to fix the above error.

../src/node_http2.cc:92:9: error: reference to non-static member
function must be called; did you mean to call
      it with no arguments...