gdb-cross: Adjust ${datadir} to avoid file conflicts in sysroot

GDB wants to install a bunch of files in ${datadir}/gdb/python/gdb and ${datadir}/gdb/syscalls. These pathnames are invariant with TARGET_ARCH which means that if you build gdb multiple times for different targets they will all try to write to the same location and you get a lot of warning spew about manifest conflicts.

Prevent this by factoring the target specification into ${datadir} so that different copies of GDB install their files into different paths.

---
 meta/recipes-devtools/gdb/gdb-cross.inc |    2 ++
 1 file changed, 2 insertions(+)

index 33feb58..a92d032 100644
@@ -10,3 +10,5 @@ GDBPROPREFIX = ""
 
 inherit cross
 inherit gettext
+
+datadir .= "/gdb-${TUNE_PKGARCH}${TARGET_VENDOR}-${TARGET_OS}"

1.7.10.4