dtrace-probe: Put semicolon after while on its own line

dtrace-probe: Put semicolon after while on its own line

clang shows this warning.

  /home/emaisin/src/binutils-gdb/gdb/dtrace-probe.c:424:52: error: while loop has empty body [-Werror,-Wempty-body]
            while (*p++ != '\0' && p - strtab < strtab_size);
                                                            ^
  /home/emaisin/src/binutils-gdb/gdb/dtrace-probe.c:424:52: note: put the semicolon on a separate line to silence this warning

Putting the semicolon on its own line is not a big sacrifice to get rid of this
warning.  I think it's also useful to keep this, because it can catch errors
like this:

  while (something);
    {
      ...
    }

although gcc would warn about it in a different way (misleading indentation).

This warning is already discussed here in the GCC bugzilla:

  https://gcc.gnu.org/bugzilla/show_bug.cgi?id=62184

gdb/ChangeLog:

	* dtrace-probe.c (dtrace_process_dof_probe): Put semi-colon on
	its own line.