perf tools: Drop CROSS_COMPILE from flex and bison calls

The flex and bison tools generate arch-independent C code so its
binaries are not prefixed with the target-arch prefix. With this patch
the Linux 3.4-rc2 can be successfuly build on OE-Core.

Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
Link: http://lkml.kernel.org/r/1334148270-13139-1-git-send-email-otavio@ossystems.com.br


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>