perf tools: Fix compatibility with libelf 0.8 and autodetect

The Makefile now automatically defines LIBELF_NO_MMAP when
libelf 0.8.x is detected. libelf 0.8 is still maintained and
some distributions such as Arch Linux use it instead of
elfutils.

Signed-off-by: Marti Raudsepp <marti@juffo.org>
Cc: Lucas De Marchi <lucas.de.marchi@gmail.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>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Mike Galbraith <efault@gmx.de>
LKML-Reference: <1256400636.3007.16.camel@newn>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

tools/perf/util/symbol.h

@@ -27,6 +27,16 @@ static inline char *bfd_demangle(void __used *v, const char __used *c,
 #endif
 #endif
 
+/*
+ * libelf 0.8.x and earlier do not support ELF_C_READ_MMAP;
+ * for newer versions we can use mmap to reduce memory usage:
+ */
+#ifdef LIBELF_NO_MMAP
+# define PERF_ELF_C_READ_MMAP ELF_C_READ
+#else
+# define PERF_ELF_C_READ_MMAP ELF_C_READ_MMAP
+#endif
+
 #ifndef DMGL_PARAMS
 #define DMGL_PARAMS      (1 << 0)       /* Include function args */
 #define DMGL_ANSI        (1 << 1)       /* Include const, volatile, etc */