Bug#792052: gcc-python-plugin: FTBFS: python3-dbg: not found

["Aaron M. Ucko" <ucko@debian.org>]

Source: gcc-python-plugin
Version: 0.14-1
Severity: serious
Justification: fails to build from source

Builds of gcc-python-plugin in minimal environments (notably, on the
autobuilders) have been failing:

  make[1]: Entering directory '/«PKGBUILDDIR»/build-python3-dbg'
  Makefile:193: warning: overriding recipe for target 'autogenerated-casts.c'
  Makefile:190: warning: ignoring old recipe for target 'autogenerated-casts.c'
  python3-dbg generate-config-h.py -o autogenerated-config.h --gcc="gcc-5" --plugindir="/usr/lib/gcc/aarch64-linux-gnu/5/plugin"
  /bin/sh: 1: python3-dbg: not found
  make[1]: *** [autogenerated-config.h] Error 127
  Makefile:177: recipe for target 'autogenerated-config.h' failed
  make[1]: Leaving directory '/«PKGBUILDDIR»/build-python3-dbg'
  make: *** [build-stamp-python3-dbg] Error 2
  dpkg-buildpackage: error: debian/rules build-arch gave error exit status 2

Please declare a build dependency on python3-dbg.

Thanks!