tools lib api: Add str_error_c to libapi

Because it uses that function, which would lead every tool using it
to need to link against tools/lib/str_error_r.o.

This fixes building tools/vm/, that links with libapi.

Reported-by: Arjan van de Ven <arjan@linux.intel.com>
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Fixes: b31e3e3316a7 ("tools lib api fs: Use str_error_r()")
Link: http://lkml.kernel.org/n/tip-aedt3qzibhnhaov2j4caqi61@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools lib api: Add debug output support

Adding support for warning/info/debug output within libapi code. Adding
following macros:

pr_warning(fmt, ...)
pr_info(fmt, ...)
pr_debug(fmt, ...)

Also adding libapi_set_print function to set above functions. This will
be used in perf to set standard debug handlers for libapi.

Adding 2 header files:
debug.h
- to be used outside libapi, contains
libapi_set_print interface

debug-internal.h
- to be used within libapi, contains
pr_warning/pr_info/pr_debug definitions

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1455465826-8426-2-git-send-email-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools lib api cpu: Introduce cpu.[ch] to obtain cpu related information

E.g.:

$ ./cpu__get_max_freq
3200000

It does that, as Kan's patch does, by looking at these files:

$ cat /sys/devices/system/cpu/online
0-3
$ ./sysfs__read_ull
devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq
/sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq=3200000
$

I.e. find out the first online CPU, then read its cpufreq info.

But do it in tools/lib/api/, so that other tools/ living code can use
it, not just perf.

Based-on-a-patch-by: Kan Liang <kan.liang@intel.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-915v4cvxqplaub8qco66b9mv@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools lib api: Rename libapikfs.a to libapi.a

Renaming libapikfs.a to libapi.a, because it's not just 'fs' specific
library now.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Tested-by: Will Deacon <will.deacon@arm.com>
Cc: Alexis Berlemont <alexis.berlemont@gmail.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-g1mk5oj2ayq4vn653ovfg3gv@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools lib api: Use tools build framework

Move the libapikfs library building under tools build framework.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Tested-by: Will Deacon <will.deacon@arm.com>
Cc: Alexis Berlemont <alexis.berlemont@gmail.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-xjo8r7nuqy9mvlfrmx9zcfwb@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>