In the Win32 crashreport handler limit the length of variable names by their
length, instead of by their 0 byte. While debugging a r1519955 related crash
I found a non zero terminated variable name here, which crashed the crash
report handler.

* subversion/libsvn_subr/win32_crashrpt.c
  (write_var_values,
   write_function_detail): Use the length of the name as limit for printf.
   We can't just copy the string here as we can't trust pools in case of a
   crash.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1532023 13f79535-47bb-0310-9956-ffa450edef68