hdf5_chunking_query_bmr

[svn-r17212] The function h5tools_str_append() incorrectly used the trio of functions: va_start(), HDvsnprintf(), and va_end(). When the boundary of the string buffer was reached and resized, the HDvsnprintf() function recalled without the other two functions in the code loop. This usage exposed bug 1520 by a user.

Tested: linux