perf tools: Add jsmn `jasmine' JSON parser

I need a JSON parser. This adds the simplest JSON parser I could find --
Serge Zaitsev's jsmn `jasmine' -- to the perf library. I merely
converted it to (mostly) Linux style and added support for non 0
terminated input.

The parser is quite straight forward and does not copy any data, just
returns tokens with offsets into the input buffer. So it's relatively
efficient and simple to use.

The code is not fully checkpatch clean, but I didn't want to completely
fork the upstream code.

Original source: http://zserge.bitbucket.org/jsmn.html

In addition I added a simple wrapper that mmaps a json file and provides
some straight forward access functions.

Used in follow-on patches to parse event files.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linuxppc-dev@lists.ozlabs.org
Link: http://lkml.kernel.org/r/1473978296-20712-2-git-send-email-sukadev@linux.vnet.ibm.com
Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
[ Use fcntl.h instead of sys/fcntl.h to fix the build on Alpine Linux 3.4/musl libc,
  use stdbool.h to avoid clashing with 'bool' typedef there ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/pmu-events/json.h

@@ -0,0 +1,32 @@
+#ifndef JSON_H
+#define JSON_H 1
+
+#include "jsmn.h"
+
+jsmntok_t *parse_json(const char *fn, char **map, size_t *size, int *len);
+void free_json(char *map, size_t size, jsmntok_t *tokens);
+int json_line(char *map, jsmntok_t *t);
+const char *json_name(jsmntok_t *t);
+int json_streq(char *map, jsmntok_t *t, const char *s);
+int json_len(jsmntok_t *t);
+
+extern int verbose;
+
+#include <stdbool.h>
+
+extern int eprintf(int level, int var, const char *fmt, ...);
+#define pr_fmt(fmt)	fmt
+
+#define pr_err(fmt, ...) \
+	eprintf(0, verbose, pr_fmt(fmt), ##__VA_ARGS__)
+
+#ifndef roundup
+#define roundup(x, y) (                                \
+{                                                      \
+        const typeof(y) __y = y;                       \
+        (((x) + (__y - 1)) / __y) * __y;               \
+}                                                      \
+)
+#endif
+
+#endif