hardwired DEBUGGER_START_FILE points to wrong location

[Nick Brown]

Currently if the environmental variable is not set then
DEBUGGER_START_FILE defaults to this;

configure.in:  DEBUGGER_START_FILE=
${ac_default_prefix}/lib/bashdb/bashdb-main.inc

However looking at the bashdb package Makefiles I note that
bashdb-main.inc will be found in $(datadir)/bashdb/, thus I think
DEBUGGER_START_FILE should default to that instead of
${ac_default_prefix}/lib/

Simply changing this to;

configure.in:  DEBUGGER_START_FILE=${datadir}/bashdb/bashdb-main.inc

does not quite work as pathname.h ends up looking like this;

#define DEBUGGER_START_FILE     "${prefix}/share/bashdb/bashdb-main.inc"

but I'm sure someone that understands autoconf/automake better can
correct this.

Thanks,
Nick