perf tools: Allow cross compiling

For embedded platforms, we want to be able to build the perf
tools on a build machine to run on a different arch. This patch
allows $CROSS_COMPILE to set the cross compiler.

Additionally, if NO_LIBPERL is set, then don't use perl include
paths as they will be for the host arch.
Signed-off-by: NJamie Iles <jamie.iles@picochip.com>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <1260523260-15694-2-git-send-email-jamie.iles@picochip.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

tools/perf/Makefile

@@ -237,8 +237,8 @@ lib = lib
 
 export prefix bindir sharedir sysconfdir
 
-CC = gcc
-AR = ar
+CC = $(CROSS_COMPILE)gcc
+AR = $(CROSS_COMPILE)ar
 RM = rm -f
 TAR = tar
 FIND = find
@@ -492,8 +492,10 @@ else
 	LIB_OBJS += util/probe-finder.o
 endif
 
+ifndef NO_LIBPERL
 PERL_EMBED_LDOPTS = `perl -MExtUtils::Embed -e ldopts 2>/dev/null`
 PERL_EMBED_CCOPTS = `perl -MExtUtils::Embed -e ccopts 2>/dev/null`
+endif
 
 ifneq ($(shell sh -c "(echo '\#include <EXTERN.h>'; echo '\#include <perl.h>'; echo 'int main(void) { perl_alloc(); return 0; }') | $(CC) -x c - $(PERL_EMBED_CCOPTS) -o /dev/null $(PERL_EMBED_LDOPTS) > /dev/null 2>&1 && echo y"), y)
 	BASIC_CFLAGS += -DNO_LIBPERL