Building gdbserver without building gdb

Hi,

I'm working in a cross-build environment and we've been happily
compiling gdbserver for our targets following the instructions on the
wiki[1]. Today I thought I'd give the latest and greatest version a
spin and found that I can't compile just gdbserver I get the following
error

  linux-low.o: In function `not_stopped_callback':
  gdb-7.9.1/gdb/gdbserver/linux-low.c:1471: undefined reference to `ptid_match'

I also tried gdb-7.8.2 with similar results. We have been happily
compiling gdbserver from gdb-7.7.1

A quick search of the source show that the call to ptid_match has been
added to gdbserver/linux-low.c in the newer versions. Any suggestions
on how to compile gdbserver independently of gdb?

Thanks,
Chris

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[1] - https://sourceware.org/gdb/wiki/BuildingCrossGDBandGDBserver