tools lib: Add bitmap_alloc function

Adding bitmap_alloc function to dynamically allocate bitmap.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20160802113302.GA7479@kravaSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/include/linux/bitmap.h

@@ -3,6 +3,7 @@
 
 #include <string.h>
 #include <linux/bitops.h>
+#include <stdlib.h>
 
 #define DECLARE_BITMAP(name,bits) \
 	unsigned long name[BITS_TO_LONGS(bits)]
@@ -65,4 +66,13 @@ static inline int test_and_set_bit(int nr, unsigned long *addr)
 	return (old & mask) != 0;
 }
 
+/**
+ * bitmap_alloc - Allocate bitmap
+ * @nr: Bit to set
+ */
+static inline unsigned long *bitmap_alloc(int nbits)
+{
+	return calloc(1, BITS_TO_LONGS(nbits) * sizeof(unsigned long));
+}
+
 #endif /* _PERF_BITOPS_H */