perf tools: Support static build

This makes it possible to build perf statically, by
performing:

  make LDFLAGS=-static

Since static libraries are only searched in the order they are
specified, move library list from LDFLAGS to EXTLIBS, so that
they are put at the end of linker command line.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <20091029152002.GA5406@redhat.com>
[ v2: resolved conflicts ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>